Category: Standard 3

Mental Maths Strategies – Standard 3 Maths

Aven Brisail1 Comment

What you will learn

  • Add quickly by finding compatible numbers that make 10, 100 or 1 000.
  • Multiply in your head using place value, factoring and tens then units.
  • Choose the best strategy for a sum and explain it.

Mental maths means working things out in your head, without writing a column sum. Good mental mathematicians do not count faster. They know some clever tricks and pick the right one. Here are six strategies to try.

A wooden abacus with beads on a shop counter
Long ago, shopkeepers used an abacus to add quickly. Today you can learn to do it in your head. Photo: Syced, CC0, via Wikimedia Commons.

1. Compatible numbers

Compatible numbers are pairs that are easy to add, such as numbers that make 10, 100 or 1 000. Look for them first.

Worked example 1

36 + 58 + 64

Show me how

Spot 36 + 64 = 100.

100 + 58 = 158.

So 36 + 58 + 64 = 158.

Other pairs: 250 + 750 = 1 000, 45 + 55 = 100, 7 + 3 = 10.

2. Place value

Say the tens or hundreds as words. 4 × 20 is 4 × 2 tens = 8 tens = 80. 3 × 300 is 3 × 3 hundreds = 9 hundreds = 900. 120 ÷ 4 is 12 tens ÷ 4 = 3 tens = 30.

3. Tens then units

Split a number into tens and units (ones). Work with the tens first, then the units, then put them together.

Worked example 2

7 × 23

Show me how

7 × 20 = 140.

7 × 3 = 21.

140 + 21 = 161.

This works for adding too: 47 + 35 is 40 + 30 = 70, and 7 + 5 = 12, so 82.

4. Factoring and doubling

Break a number into factors and multiply in steps. 6 × 8 is 6 × 2 × 4: 12 × 4 = 48. To multiply by 4, double and double again: 4 × 35 is 70, then 140.

Worked example 3

5 × 18

Show me how

18 = 2 × 9.

5 × 2 = 10.

10 × 9 = 90.

5. Equal addends

Equal addends are numbers that are the same. 25 + 25 + 25 + 25 is 4 × 25 = 100. Doubles near doubles help too: 26 + 25 is 25 + 25 + 1 = 51.

Watch out! A common mistake

Do not try one strategy for everything. For 299 + 145, it is quicker to think 300 + 145 = 445, then take 1 away to get 444. Stop and look at the numbers first.

6. Facts to 10 × 10

All of these strategies need your times tables. Keep practising your facts to 10 × 10 in Lesson 11 so that they come quickly.

Try it

TRY ITMental maths trainer

Pick a strategy. Each question shows the quick way after you answer. Try Name the strategy when you are ready.

Let’s practise

Work out each one in your copybook. Open Hint if you are stuck, then open Show answer to check your working.

1. Work out 27 + 45 + 73.

Hint

Which two make 100?

Show answer

27 + 73 = 100, so 145.

2. What is 6 × 30?

Hint

6 × 3 tens.

Show answer

18 tens = 180

3. What is 800 ÷ 4?

Hint

8 hundreds ÷ 4.

Show answer

2 hundreds = 200

4. Work out 6 × 14 using tens then units.

Hint

6 × 10 and 6 × 4.

Show answer

60 + 24 = 84

5. Work out 4 × 45 by doubling.

Hint

Double 45, then double again.

Show answer

90, then 180

6. What is 15 + 15 + 15 + 15?

Hint

4 equal addends.

Show answer

4 × 15 = 60

7. Work out 499 + 238.

Hint

Think of 500.

Show answer

500 + 238 = 738, take 1: 737

8. Which strategy would you use for 125 + 368 + 875? Why?

Hint

Look for a pair that makes 1 000.

Show answer

Compatible numbers: 125 + 875 = 1 000, so 1 368.

Quiz

Lesson quiz: 10 questions

Answer every question, then press Check my answers. Score 8 or more to earn the Mental Maths Master badge.

Recap

  • Compatible numbers: look for pairs that make 10, 100 or 1 000.
  • Place value: 4 × 20 = 8 tens = 80.
  • Tens then units: 7 × 23 = 140 + 21.
  • Factoring and doubling: 5 × 18 = 10 × 9.
  • Equal addends: 25 + 25 + 25 + 25 = 4 × 25.
  • Look at the numbers first, then choose a strategy.

Words to know

mental maths
Working out answers in your head.
Example: I did 50 × 3 by mental maths.
compatible numbers
Numbers that are easy to put together.
Example: 70 and 30 are compatible numbers.
factor
A number that multiplies to make another.
Example: 2 and 9 are factors of 18.
addend
A number being added.
Example: In 5 + 4, the addends are 5 and 4.
strategy
A plan or a clever way to solve a problem.
Example: My strategy was tens then units.

Try it at home

  • At the market, add the prices of two or three items in your head before the vendor tells you the total.
  • Mini project: make a poster of your three favourite mental maths strategies, with one example of each.

Test tips

Tips for class tests

  • Look at the numbers before you start. Is there a pair that makes 100?
  • Check a mental answer with a different strategy.
  • Keep your times tables sharp. They make every strategy faster.

For parents and teachers

After this lesson, your child should be able to:

  • use compatible numbers within 1 000;
  • use place value, factoring, tens then units and equal addends to calculate mentally;
  • recall facts to 10 × 10 and choose and explain a strategy.

These are the mental strategies named in the guide. Ask your child to say how they did a sum. There is often more than one good way, and explaining it builds number sense.

Quiz scores and badges are saved only in this browser on this device. Nothing is sent anywhere. If the browser data is cleared, or another device is used, the badges will be lost.

Previous: Multiplication and Division Word Problems – Standard 3 Maths
Next: Equivalent Fractions and Lowest Terms (coming soon)
Course: Standard 3 Maths

Updates

2026/11/04
– First version of this lesson.

Attributions to media used in this post:

Abacus actually in use at kimono shop in Otaru.jpg – Syced – CC0 1.0 (via Wikimedia Commons)

© 2026 Vedesh Kungebeharry. All rights reserved.

Multiplication and Division Word Problems – Standard 3 Maths

Aven Brisail2 Comments

What you will learn

  • Decide whether a word problem needs multiplication or division.
  • Solve rate problems: per hour, per day, per week and per month.
  • Use the unitary method, make sense of remainders and check with an estimate.

Word problems hide the maths inside a story. Your job is to find the numbers, decide what to do with them, work it out and then check that the answer makes sense. In this lesson the stories are about pay, prices, sharing and packing, all in TT dollars.

Fishermen in a pirogue heading out to sea from King’s Wharf, San Fernando
Fishermen leave King’s Wharf in San Fernando. If a boat brings in 45 kg of fish a day, how much is that in 6 days? Photo: Kalamazadkhan, CC BY-SA 3.0, via Wikimedia Commons.

Multiply or divide?

Read the story twice. Ask: am I putting equal groups together, or splitting a total into equal groups?

  • Multiply when you know one group and how many groups: each, every, per, a day, a week, in all.
  • Divide when you know the total and need one share or the number of groups: share, equally, each get, how many in each, how many boxes.

Rates: per hour, per day, per week

A rate is an amount for each hour, day, week, month or year. If you know the rate, multiply to find the total. If you know the total, divide to find the rate.

Worked example 1

Mr Mohammed earns $45 an hour. He works 8 hours. How much does he earn?

Show me how

The rate is $45 for each hour, for 8 hours.

8 × $45 = 8 × 40 + 8 × 5 = 320 + 40 = $360.

He earns $360.

Worked example 2

Ms Charles is paid $1 400 for 4 weeks. How much is that each week?

Show me how

Total ÷ number of weeks.

$1 400 ÷ 4 = $350.

She is paid $350 a week.

Remember: 1 week = 7 days, 1 year = 12 months, 1 hour = 60 minutes. A phone plan at 3 cents a minute costs 3 × 20 = 60 cents for 20 minutes.

The unitary method

Unitary means one. First find the value of one, then multiply to find any number.

Worked example 3

5 exercise books cost $40. How much do 8 cost?

Show me how

One book: $40 ÷ 5 = $8.

Eight books: 8 × $8 = $64.

8 exercise books cost $64.

What does the remainder mean?

In a story, think about what the remainder means. 50 children go on a trip and each maxi taxi takes 12. 50 ÷ 12 = 4 r 2. Four taxis are full, but the 2 children left over still need a ride, so you need 5 taxis. If you are filling boxes of 12 cakes from 50, only 4 boxes are full.

Watch out! A common mistake

Do not just copy the number from the division. Read the question again: does it ask for full groups, for groups needed for everyone, or for what is left over?

Check with an estimate. For 48 × 6, think 50 × 6 = 300. An answer of 288 is close, but 2 880 is far too big.

Try it

TRY ITWord problem workout

Solve story problems about pay, prices, taxis and boxes. Read each one carefully before you choose.

TRY ITNumber story builder

Pick a story and the numbers, then tell someone the number story and work it out. Open Show the working to check.

Let’s practise

Work out each one in your copybook. Open Hint if you are stuck, then open Show answer to check your working.

1. A gardener earns $60 a day. How much does he earn in 5 days?

Hint

Multiply: 5 × $60.

Show answer

$300

2. Keisha is paid $480 for 4 weeks. How much is that each week?

Hint

Divide: $480 ÷ 4.

Show answer

$120

3. Internet costs $199 a month. How much for 3 months?

Hint

3 × $199 is about 3 × $200.

Show answer

$597

4. 6 bottles of juice cost $42. How much do 9 bottles cost?

Hint

Find one bottle first: $42 ÷ 6.

Show answer

$7 each, so 9 cost $63.

5. 75 children go to the zoo. A bus holds 20. How many buses are needed?

Hint

75 ÷ 20 = 3 r 15. Do the 15 children stay home?

Show answer

4 buses

6. A baker has 100 rolls and packs them in bags of 8. How many full bags?

Hint

100 ÷ 8 = 12 r 4.

Show answer

12 full bags, with 4 rolls left over.

7. Ravi says 52 × 4 = 2 008. Use an estimate to check.

Hint

52 is about 50.

Show answer

50 × 4 = 200, so 2 008 is too big. The answer is 208.

8. Write a number story for 6 × $25 = $150.

Hint

Use the words each or a day.

Show answer

For example: A taxi fare is $25 a day. In 6 days I spend $150.

Quiz

Lesson quiz: 10 questions

Answer every question, then press Check my answers. Score 8 or more to earn the Problem Solver badge.

Recap

  • Multiply to put equal groups together. Divide to share or make equal groups.
  • Rate: an amount per hour, day, week, month or year. Total = rate × time.
  • Unitary method: find the value of one, then multiply.
  • Decide what the remainder means in the story.
  • Estimate to check that your answer makes sense.

Words to know

rate
An amount for each hour, day, week or other unit.
Example: The rate is $40 a day.
per
For each.
Example: Bananas cost $2 per pound.
unitary method
Finding the value of one first.
Example: I used the unitary method to price 7 pens.
equally
In the same amounts.
Example: We shared the money equally.
reasonable
Makes sense and is close to the estimate.
Example: 208 is a reasonable answer for 52 × 4.

Try it at home

  • Ask an adult about a weekly or monthly bill, such as bus fare or phone credit. Work out what it costs for a month or a year.
  • Mini project: plan a class trip for 35 children. Choose maxi taxis that take 12 or buses that take 30. How many do you need, and which leaves fewer empty seats?

Test tips

Tips for class tests

  • Underline the numbers and circle the key words: each, per, share, equally, in all.
  • Write a number sentence before you work it out.
  • After dividing, read the question again to decide what the remainder means.

For parents and teachers

After this lesson, your child should be able to:

  • decide whether a word problem needs multiplication or division;
  • solve rate problems by the hour, day, week, month and year, and by the minute in cents;
  • use the unitary method, interpret remainders and check with an estimate.

As the guide asks, money is in whole dollars or whole cents only. Real bills, pay slips or price lists from home make the stories feel real. Ask your child to explain how they got each answer.

Quiz scores and badges are saved only in this browser on this device. Nothing is sent anywhere. If the browser data is cleared, or another device is used, the badges will be lost.

Previous: Division and Remainders – Standard 3 Maths
Next: Mental Maths Strategies – Standard 3 Maths
Course: Standard 3 Maths

Updates

2026/11/04
– First version of this lesson.

Attributions to media used in this post:

Fishing Boat, King’s Wharf, San Fernando, Trinidad and Tobago.JPG – Kalamazadkhan – CC BY-SA 3.0 (via Wikimedia Commons)

© 2026 Vedesh Kungebeharry. All rights reserved.

Division and Remainders – Standard 3 Maths

Aven Brisail2 Comments

What you will learn

  • Divide by sharing equally and by making equal groups.
  • Use times tables to find division facts.
  • Divide numbers up to 9 999 by a 1-digit number and explain the remainder.

Division means sharing equally or putting things into equal groups. Sometimes things share out exactly. Sometimes a few are left over, and that left over part is called the remainder. In this lesson you will divide big numbers one digit at a time and check your answers with multiplication.

A white maxi taxi with a coloured band waiting for passengers in Trinidad
A Chaguanas to Couva maxi taxi waiting for passengers. How many maxi taxis does a class trip need? Photo: Zagaboy, CC0, via Wikimedia Commons.

Sharing and grouping

The sign ÷ means divided by. 12 ÷ 3 can mean share 12 sweets between 3 children (each gets 4), or make groups of 3 from 12 sweets (you make 4 groups). Both give 4.

Division undoes multiplication. If you know 6 × 7 = 42, you also know 42 ÷ 6 = 7 and 42 ÷ 7 = 6. These are a fact family.

Remainders

Share 14 mangoes between 4 bags. Each bag gets 3 mangoes, which uses 12. There are 2 left over, not enough to go round again. We write 14 ÷ 4 = 3 remainder 2, or 3 r 2.

Worked example 1

18 ÷ 4

Show me how

Count in 4s: 4, 8, 12, 16. The next one, 20, is too many.

4 × 4 = 16, so the answer is 4.

18 − 16 = 2 are left. 18 ÷ 4 = 4 remainder 2.

Watch out! A common mistake

The remainder must always be less than the number you divide by. If you get 23 ÷ 5 = 3 r 8, the 8 is too big: another 5 can still be shared. The answer is 4 r 3.

Short division, one digit at a time

For bigger numbers, start on the left. Divide each digit, write the answer on top, and carry what is left over to the next digit. This is the same as long division: divide, multiply, take away, bring down.

Worked example 2

745 ÷ 3

Show me how

Hundreds: 7 ÷ 3 = 2, because 3 × 2 = 6. 7 − 6 = 1 left. Carry 1 to make 14.

Tens: 14 ÷ 3 = 4, because 3 × 4 = 12. 14 − 12 = 2 left. Carry 2 to make 25.

Ones: 25 ÷ 3 = 8, because 3 × 8 = 24. 25 − 24 = 1 left.

So 745 ÷ 3 = 248 remainder 1.

Worked example 3

2 436 ÷ 6

Show me how

2 is less than 6, so look at 24. 24 ÷ 6 = 4, nothing left.

3 ÷ 6 = 0. Write 0 on top, carry 3 to make 36.

36 ÷ 6 = 6.

So 2 436 ÷ 6 = 406.

Check with multiplication

To check a division, multiply the answer by the number you divided by, then add the remainder. You should get back the number you started with. For 745 ÷ 3 = 248 r 1: 248 × 3 = 744, and 744 + 1 = 745. It checks.

Try it

TRY ITShort division stepper

Divide one digit at a time, from the left. Small red numbers are the remainders you carry.

TRY ITShare, divide and check

Share sweets fairly, use times tables for division facts, and check answers with multiplication.

Let’s practise

Work out each one in your copybook. Open Hint if you are stuck, then open Show answer to check your working.

1. What is 56 ÷ 8?

Hint

Which number times 8 makes 56?

Show answer

7

2. Share 23 marbles between 5 friends. How many each, and how many left?

Hint

Count in 5s up to 23.

Show answer

4 each, 3 left. 23 ÷ 5 = 4 r 3.

3. Work out 96 ÷ 4.

Hint

9 ÷ 4 = 2 r 1. Carry 1 to make 16.

Show answer

24

4. Work out 587 ÷ 5.

Hint

5 ÷ 5 = 1. Then 8 ÷ 5 = 1 r 3, carry 3.

Show answer

117 remainder 2

5. Work out 3 248 ÷ 8.

Hint

3 is less than 8, so look at 32 first.

Show answer

406

6. Check: is 157 ÷ 6 = 26 r 1 right?

Hint

Work out 26 × 6, then add 1.

Show answer

26 × 6 = 156 and 156 + 1 = 157. Yes, it is right.

7. Asha says 38 ÷ 7 = 4 r 10. What is wrong?

Hint

Is the remainder smaller than 7?

Show answer

The remainder 10 is bigger than 7. The answer is 5 r 3.

8. Write the fact family for 9, 6 and 54.

Hint

Two multiplications and two divisions.

Show answer

9 × 6 = 54, 6 × 9 = 54, 54 ÷ 9 = 6, 54 ÷ 6 = 9.

Quiz

Lesson quiz: 10 questions

Answer every question, then press Check my answers. Score 8 or more to earn the Fair Sharer badge.

Recap

  • ÷ means share equally or make equal groups.
  • Division undoes multiplication: 6 × 7 = 42, so 42 ÷ 7 = 6.
  • The remainder is what is left over. It is always less than the number you divide by.
  • Short division: start on the left, divide each digit, carry what is left.
  • Check: answer × divisor + remainder = the number you started with.

Words to know

divide
To share equally or make equal groups.
Example: We divided 20 pens between 4 tables.
remainder
The amount left over after dividing.
Example: 17 ÷ 5 = 3 remainder 2.
divisor
The number you divide by.
Example: In 45 ÷ 9, the divisor is 9.
quotient
The answer to a division.
Example: The quotient of 24 ÷ 6 is 4.
fact family
Related multiplication and division facts.
Example: 3, 8 and 24 make a fact family.

Try it at home

  • Share a pack of biscuits or a bag of grapes equally between the people at home. How many each? How many are left?
  • Mini project: a family of 4 has $250 to spend in 4 weeks. Work out how much they can spend each week, and what is left.

Test tips

Tips for class tests

  • Always check that the remainder is less than the divisor.
  • Use your times tables. Division facts are times tables backwards.
  • Check by multiplying back. Then add the remainder.

For parents and teachers

After this lesson, your child should be able to:

  • explain division as sharing and grouping;
  • divide numbers up to 9 999 by a 1-digit number, with remainders;
  • check a division by multiplying back and adding the remainder.

The guide asks for division up to 4 digits by 1 digit and for children to explain why a remainder appears. We teach short division and say each step in long-division words (divide, multiply, take away, bring down). Counters, beans or bottle caps are great for sharing.

Quiz scores and badges are saved only in this browser on this device. Nothing is sent anywhere. If the browser data is cleared, or another device is used, the badges will be lost.

Previous: Multiplying Bigger Numbers – Standard 3 Maths
Next: Multiplication and Division Word Problems – Standard 3 Maths
Course: Standard 3 Maths

Updates

2026/11/04
– First version of this lesson.

Attributions to media used in this post:

Maxitaxi new.jpg – Zagaboy – CC0 1.0 (via Wikimedia Commons)

© 2026 Vedesh Kungebeharry. All rights reserved.

Multiplying Bigger Numbers – Standard 3 Maths

Aven Brisail1 Comment

What you will learn

  • Multiply by 10 and 100, and by multiples of 10 such as 30.
  • Use the area model to split a number into tens and ones.
  • Multiply in columns by a 1-digit number, and 2 digits by 2 digits.

Now that you know your facts to 10 × 10, you can multiply much bigger numbers. The secret is to split a big number into tens and ones, multiply each part with a fact you know, and add. The column method does the same thing in a short, tidy way.

A baking tray of chocolate muffins in equal rows
Muffins are baked in rows. If one tray holds 12, then 14 trays hold 14 × 12 = 168 muffins. Photo: Ceeseven, CC BY-SA 4.0, via Wikimedia Commons.

Times 10, times 100 and tens

When you multiply by 10, every digit moves one place to the left and a 0 fills the ones place: 34 × 10 = 340. Times 100 moves the digits two places: 34 × 100 = 3 400.

To multiply by 30, think 3 × 10. So 6 × 30 = 6 × 3 × 10 = 18 × 10 = 180.

The area model

Split the bigger number into tens and ones. Multiply each part, then add the parts. This is how the column method works.

Worked example 1

23 × 4

Show me how

Split 23 into 20 and 3.

20 × 4 = 80 and 3 × 4 = 12.

80 + 12 = 92. So 23 × 4 = 92.

The column method

Write the 1-digit number under the ones. Multiply the ones first. If the answer is 10 or more, write the ones digit and carry the tens to the next column. Add the carried number after you multiply that column.

Worked example 2

347 × 6

Show me how

Ones: 7 × 6 = 42. Write 2, carry 4.

Tens: 4 × 6 = 24, plus 4 carried = 28. Write 8, carry 2.

Hundreds: 3 × 6 = 18, plus 2 carried = 20. Write 20.

The answer is 2 082.

Watch out! A common mistake

Multiply first, then add the carried number. In 347 × 6 the tens column is 4 × 6 + 4 = 28, not (4 + 4) × 6 = 48.

2 digits by 2 digits

For 34 × 26, multiply by the 6 ones, then by the 2 tens, and add the two lines. On the second line write a 0 in the ones first, because you are multiplying by 20.

Worked example 3

34 × 26

Show me how

34 × 6 = 204.

34 × 20 = 680. Write the 0, then 34 × 2 = 68.

204 + 680 = 884. So 34 × 26 = 884.

Try it

TRY ITColumn multiplication stepper

Work through each sum one step at a time. The yellow column is the one you are working on.

TRY ITArea model and tens

Split a number into tens and ones, or multiply by 10, 100 or a multiple of 10.

Let’s practise

Work out each one in your copybook. Open Hint if you are stuck, then open Show answer to check your working.

1. What is 56 × 10?

Hint

A 0 goes on the end.

Show answer

560

2. What is 7 × 40?

Hint

7 × 4 = 28, then × 10.

Show answer

280

3. Use the area model for 36 × 5.

Hint

30 × 5 and 6 × 5.

Show answer

150 + 30 = 180

4. Work out 48 × 7 in columns.

Hint

Ones: 8 × 7 = 56. Write 6, carry 5.

Show answer

336

5. Work out 1 205 × 4.

Hint

Remember the 0 tens: 0 × 4 + carried.

Show answer

4 820

6. A school orders 24 boxes of chalk. Each box has 12 sticks. How many sticks?

Hint

24 × 12: 24 × 2, then 24 × 10.

Show answer

48 + 240 = 288 sticks

7. Work out 53 × 31.

Hint

53 × 1, then 53 × 30.

Show answer

53 + 1 590 = 1 643

8. Tim says 62 × 3 = 1 806. What did he do wrong?

Hint

Did he carry correctly? 62 is 60 + 2.

Show answer

He wrote 18 and 6 side by side. 60 × 3 = 180 and 2 × 3 = 6, so 62 × 3 = 186.

Quiz

Lesson quiz: 10 questions

Answer every question, then press Check my answers. Score 8 or more to earn the Multiplication Builder badge.

Recap

  • Times 10: a 0 on the end. Times 100: two zeros.
  • Split numbers into tens and ones, multiply each part, then add.
  • Column method: multiply the ones first, carry, and add the carried number after multiplying.
  • 2 digits by 2 digits: multiply by the ones, then by the tens (write the 0 first), then add.

Words to know

multiple of 10
A number you get by multiplying by 10, such as 30 or 70.
Example: 40 is a multiple of 10.
area model
A rectangle split into parts to help you multiply.
Example: I used an area model for 23 × 4.
carry
Move a ten to the next column.
Example: 7 × 6 = 42, so I wrote 2 and carried 4.
long multiplication
Multiplying by a 2-digit number with two lines and adding them.
Example: 34 × 26 is long multiplication.
estimate
A close answer found quickly.
Example: 62 × 3 is about 60 × 3 = 180.

Try it at home

  • Count the eggs, juice boxes or tins in a pack. Work out how many there would be in 12 packs.
  • Mini project: plan a class bake sale with trays of 12 cupcakes. Work out how many cupcakes 15, 24 and 35 trays make.

Test tips

Tips for class tests

  • Estimate first: 48 × 7 is about 50 × 7 = 350. Your answer should be close.
  • Keep the digits in straight columns and write carried numbers small.
  • In long multiplication, do not forget the 0 on the second line.

For parents and teachers

After this lesson, your child should be able to:

  • multiply by 10, 100 and multiples of 10;
  • multiply 2-, 3- and 4-digit numbers by a 1-digit number in columns;
  • multiply 2 digits by 2 digits using the area model or long multiplication.

The guide asks for multiplication up to 2 digits by 2 digits. The 3- and 4-digit by 1-digit work stays below 10 000. Squared paper helps to keep the columns straight.

Quiz scores and badges are saved only in this browser on this device. Nothing is sent anywhere. If the browser data is cleared, or another device is used, the badges will be lost.

Previous: Multiplication Facts to 10 × 10 – Standard 3 Maths
Next: Division and Remainders – Standard 3 Maths
Course: Standard 3 Maths

Updates

2026/11/04
– First version of this lesson.

Attributions to media used in this post:

Tray of Chocolate Muffins.jpg – Ceeseven – CC BY-SA 4.0 (via Wikimedia Commons)

© 2026 Vedesh Kungebeharry. All rights reserved.

Multiplication Facts to 10 × 10 – Standard 3 Maths

Aven Brisail2 Comments

What you will learn

  • Show a multiplication fact as equal groups and as an array.
  • Know the times tables from 2 × 1 up to 10 × 10.
  • Use turn-around facts and facts you know to find harder ones.

Multiplication is a quick way to add equal groups. Instead of adding 4 + 4 + 4 + 4 + 4, you can say 5 groups of 4, or 5 × 4 = 20. In this lesson you will build arrays, learn tricks for each times table and practise the facts up to 10 × 10 until they come quickly.

Egg cartons full of brown chicken eggs, set out in neat rows
Eggs in a carton sit in rows. A carton with 2 rows of 6 holds 2 × 6 = 12 eggs. Photo: Krzysztof Golik, CC BY-SA 4.0, via Wikimedia Commons.

Equal groups and arrays

The sign × means times or groups of. In 3 × 5 = 15, the numbers 3 and 5 are factors and 15 is the product.

An array is a set of objects in equal rows. Count the rows, count how many are in one row, then multiply.

3 rows of 5 = 3 × 5 = 15

Worked example 1

A tray of sweet bread buns has 4 rows with 6 buns in each row. How many buns are there?

Show me how

There are 4 rows of 6.

Skip count in 6s: 6, 12, 18, 24.

4 × 6 = 24 buns.

Rows of solar panels on a roof, set out in equal rows and columns
Solar panels are often set out in an array. Count the rows and the panels in one row, then multiply. Photo: Pujanak, public domain, via Wikimedia Commons.

Turn-around facts

Turn an array on its side and you get the same number of dots. So 3 × 5 and 5 × 3 are both 15. This means you only need to learn about half of the facts. If you know 8 × 2 = 16, you also know 2 × 8 = 16.

Watch out! A common mistake

Do not mix up × and +. 4 × 3 means 4 groups of 3, which is 12. It is not 4 + 3 = 7. Read the sign before you answer.

Tricks for each table

Use what you already know to find harder facts:

  • × 2: double the number. × 4: double, then double again.
  • × 5: the answer ends in 0 or 5. × 10: put a 0 on the end.
  • × 9: work out × 10, then take one group away. 9 × 7 = 70 − 7 = 63.
  • × 3, × 6, × 7, × 8: build from a fact you know. 6 × 7 = 5 × 7 + 7 = 35 + 7 = 42.

Worked example 2

What is 8 × 6?

Show me how

8 × 6 is double 4 × 6.

4 × 6 = 24, and double 24 is 48.

So 8 × 6 = 48.

Worked example 3

What is 9 × 8?

Show me how

10 × 8 = 80.

9 groups is one group less: 80 − 8 = 72.

So 9 × 8 = 72.

Try it

TRY ITTimes table practice

Practise the facts up to 10 × 10. Pick one table or All. The timed round is optional and only compares you with your own best.

TRY ITArray builder

Add or take away rows and columns to build the array, then check it. Or match an array to its number sentence.

Let’s practise

Work out each one in your copybook. Open Hint if you are stuck, then open Show answer to check your working.

1. What is 7 × 4?

Hint

Double 7, then double again.

Show answer

28

2. An array has 5 rows of 8 chairs. How many chairs?

Hint

5 × 8. Count in 8s five times.

Show answer

40 chairs

3. You know 6 × 9 = 54. What is 9 × 6?

Hint

Turn-around facts give the same product.

Show answer

54

4. Use 10 × 7 = 70 to find 9 × 7.

Hint

Take one group of 7 away.

Show answer

70 − 7 = 63

5. Fill the box: 8 × = 56.

Hint

Count in 8s until you reach 56.

Show answer

7, because 8 × 7 = 56.

6. A packet holds 6 crackers. How many crackers in 9 packets?

Hint

9 × 6.

Show answer

54 crackers

7. Which is bigger: 7 × 8 or 6 × 9?

Hint

Work out both. 7 × 8 = 56.

Show answer

7 × 8 = 56 is bigger than 6 × 9 = 54.

8. Write two multiplication facts for an array of 4 rows of 10.

Hint

Turn the array round.

Show answer

4 × 10 = 40 and 10 × 4 = 40.

Quiz

Lesson quiz: 10 questions

Answer every question, then press Check my answers. Score 8 or more to earn the Times Table Star badge.

Recap

  • × means groups of. In 4 × 5 = 20, 4 and 5 are factors and 20 is the product.
  • An array has equal rows. Rows × number in each row = total.
  • Turn-around facts: 3 × 8 = 8 × 3.
  • Use facts you know: double for × 4 and × 8, × 10 then take one group for × 9.

Words to know

multiply
To add equal groups quickly.
Example: When we multiply 4 by 3 we get 12.
factor
A number that is multiplied.
Example: In 6 × 4 = 24, 6 and 4 are factors.
product
The answer to a multiplication.
Example: The product of 5 and 6 is 30.
array
Objects set out in equal rows and columns.
Example: The chairs made an array of 5 rows of 6.
times table
A list of the multiples of one number.
Example: I said the 7 times table to Granny.

Try it at home

  • Look for arrays at home: egg cartons, tiles, windows, a box of juice. Say the multiplication fact for each one.
  • Mini project: make your own times-table chart from 1 × 1 to 10 × 10 on a sheet of paper. Colour all the turn-around pairs the same colour.

Test tips

Tips for class tests

  • If you forget a fact, build it from one you know. Do not guess.
  • Check the sign. × and + give very different answers.
  • Learn the hard ones first: 6 × 7, 6 × 8, 7 × 8, 8 × 8, 7 × 9.

For parents and teachers

After this lesson, your child should be able to:

  • explain multiplication as equal groups and arrays;
  • recall multiplication facts up to 10 × 10;
  • use turn-around facts, doubling and known facts to work out others.

Short, regular practice works best: five minutes a day of mixed facts. The timed round is optional and only compares a child with their own best score on this device, never with other children.

Quiz scores and badges are saved only in this browser on this device. Nothing is sent anywhere. If the browser data is cleared, or another device is used, the badges will be lost.

Previous: Money Problems: Bills, Best Buy, Profit and Loss – Standard 3 Maths
Next: Multiplying Bigger Numbers – Standard 3 Maths
Course: Standard 3 Maths

Updates

2026/11/04
– First version of this lesson.

Attributions to media used in this post:

Egg cartons with chicken eggs 03.jpg – Krzysztof Golik – CC BY-SA 4.0 (via Wikimedia Commons)

Solar panels on a roof.jpg – Pujanak – Public domain (via Wikimedia Commons)

© 2026 Vedesh Kungebeharry. All rights reserved.

Money Problems: Bills, Best Buy, Profit and Loss – Standard 3 Maths

Aven Brisail1 Comment

What you will learn

  • Add up a bill and work out the change.
  • Compare two offers to find the best buy.
  • Work out profit or loss from the cost and the takings.

In this lesson you will use adding and subtracting to solve money problems: bills, change, best buys and profit or loss. All prices are in TT dollars, using whole dollars or whole cents.

A roadside stall in south Trinidad with coconuts, pineapples, bananas, green fig and tomatoes
A fruit and vegetable stall in south Trinidad. Does the owner make a profit? Photo: 999real, CC0, via Wikimedia Commons.

Bills and change

A bill lists what you bought and the cost of each thing. Add the amounts to find the total. To find your change, take the total away from the money you paid.

2 doubles at $6$12

1 coconut water$10

1 aloo pie$5

Total$27

Worked example 1

You buy the food on the bill above and pay with $50. What is your change?

Show me how

Total: $12 + $10 + $5 = $27.

Change: $50 − $27 = $23.

You get $23 change.

A doubles vendor at Debe market serving customers from a stall
A doubles vendor at Debe market. Photo: Kalamazadkhan, CC BY-SA 3.0, via Wikimedia Commons.

Small amounts are in cents. 100 cents make $1. A sugar cake at 45 cents and a lollipop at 30 cents cost 75 cents. From $1 the change is 100 − 75 = 25 cents.

A silver Trinidad and Tobago 25 cent coin
A Trinidad and Tobago 25 cent coin. 100 cents make $1. Photo: Mark Morgan from Trinidad, CC BY 2.0, via Wikimedia Commons.

Best buy

The best buy is the offer that costs less for the same amount of things.

Worked example 2

You need 6 juice boxes. Shop A sells them at $4 each. Shop B sells a pack of 6 for $21.

Show me how

Shop A: $4 + $4 + $4 + $4 + $4 + $4 = $24.

Shop B: $21.

Shop B is the best buy. You save $24 − $21 = $3.

Watch out! A common mistake

The smallest price tag is not always the best buy. A pack of 3 for $10 looks cheaper than a pack of 6 for $18, but two packs of 3 cost $20.

Profit and loss

A seller pays for stock. That is the cost. The money from selling is the takings. If the takings are more than the cost, the seller makes a profit. If they are less, it is a loss.

Worked example 3

Mr Joseph buys 10 coconuts for $50. He sells every one for $8.

Show me how

Takings: 10 lots of $8 = $80.

$80 is more than $50, so he makes a profit.

Profit: $80 − $50 = $30.

A school fair spent $1 250 on stock and took in $1 175. That is less, so it is a loss of $1 250 − $1 175 = $75.

Try it

TRY ITTuck shop maths

Add up bills, give change, pick the best buy and work out profit or loss. Prices are in TT dollars.

TRY ITRun the tuck shop

Buy stock, choose a price and open the shop. Too high a price means fewer children buy. Can you make a profit? How to use it: pick your stock, pick a price, then press Open the shop. Try each price and compare the profits.

Let’s practise

Work out each one in your copybook. Open Hint if you are stuck, then open Show answer to check your working.

1. Add the bill: 3 currants rolls at $8 each and 1 bottle of water at $3.

Hint

$8 + $8 + $8, then add $3.

Show answer

$27

2. Your bill is $64. You pay with $100. What is your change?

Hint

$100 − $64.

Show answer

$36

3. A sugar cake costs 45 cents. You pay with $1. What is your change?

Hint

$1 is 100 cents.

Show answer

55 cents

4. You need 10 bottles of water. Shop A: $3 each. Shop B: a pack of 10 for $25. Which is the best buy?

Hint

Work out 10 bottles at Shop A.

Show answer

Shop A costs $30, Shop B $25. Shop B saves $5.

5. Which is the best buy for 8 rolls: a pack of 4 for $18, or a pack of 8 for $34?

Hint

Two packs of 4 cost $18 + $18.

Show answer

Two packs of 4 cost $36, so the pack of 8 saves $2.

6. Aunty Lisa buys 20 mangoes for $50. She sells them all and the takings are $60. Profit or loss?

Hint

Compare $60 with $50.

Show answer

Profit of $10

7. Uncle Dev spent $1 500 on stock for a school fair and took in $1 365. Profit or loss, and how much?

Hint

Is $1 365 more or less than $1 500?

Show answer

Loss of $135

8. Write a number story about lunch where you pay with $50 and get $12 change.

Hint

Your food must cost $38.

Show answer

For example: I paid $50 for lunch costing $38 and got $12 change.

Quiz

Lesson quiz: 10 questions

Answer every question, then press Check my answers. Score 8 or more to earn the Tuck Shop Boss badge.

Recap

  • Add the amounts on a bill to find the total.
  • Change = money paid − total.
  • 100 cents make $1.
  • For the best buy, compare the cost of the same amount.
  • Takings more than cost is a profit. Takings less than cost is a loss.

Words to know

bill
A list of things bought and what they cost.
Example: The bill for lunch was $27.
change
Money you get back when you pay too much.
Example: I paid $50 and got $23 change.
takings
The money a seller gets from selling.
Example: The tuck shop takings were $80.
profit
Money made when takings are more than cost.
Example: We made a profit of $30.
loss
Money lost when takings are less than cost.
Example: The stall made a loss of $75.

Try it at home

  • At a shop or market, add up the bill before the cashier does and work out the change.
  • Mini project: plan a pretend tuck shop with 3 things to sell. Choose the cost of the stock and your prices. Work out the profit if you sell everything.

Test tips

Tips for class tests

  • Underline the numbers and the key words: total, change, cheaper, profit, loss.
  • Write the dollar sign in your answer, or the word cents.
  • For best buy questions, write the cost at each shop before you decide.

For parents and teachers

After this lesson, your child should be able to:

  • add amounts on a bill and work out change, in whole dollars or whole cents;
  • compare offers to find the best buy;
  • decide if a sale makes a profit or a loss, and by how much.

As the guide asks, amounts are in dollars only or cents only, with no decimals. Real coins and receipts help a lot.

Quiz scores and badges are saved only in this browser on this device. Nothing is sent anywhere. If the browser data is cleared, or another device is used, the badges will be lost.

Previous: Checking Answers: Estimation and the Inverse – Standard 3 Maths
Next: Multiplication Facts to 10 × 10 – Standard 3 Maths
Course: Standard 3 Maths

Updates

2026/11/04
– Linked the Next lesson.
– Improved the hints in the Run the tuck shop game.
– First version of this lesson.

Attributions to media used in this post:

A fruit and vegetable stall in South Trinidad selling coconuts, coconut water, pineapple, bananas, green fig, tomatoes and more.jpg – 999real – CC0 1.0 (via Wikimedia Commons)

Doubles Vendor, Debe Market, Trinidad and Tobago.JPG – Kalamazadkhan – CC BY-SA 3.0 (via Wikimedia Commons)

25 Trinidad and Tobago Cents (5106278120).jpg – Mark Morgan from Trinidad – CC BY 2.0 (via Wikimedia Commons)

© 2026 Vedesh Kungebeharry. All rights reserved.

Checking Answers: Estimation and the Inverse – Standard 3 Maths

Aven Brisail1 Comment

What you will learn

  • Estimate a sum or difference by rounding to the nearest hundred.
  • Decide if an answer is reasonable.
  • Check addition by subtracting, and subtraction by adding.

Good mathematicians always check their work. In this lesson you will learn two checks. An estimate tells you if an answer is about right. The inverse tells you if it is exactly right.

A small grey pocket calculator with a solar panel and number keys
Even with a calculator, it is easy to press a wrong key. A quick estimate tells you if the answer makes sense. Photo: LoMit, CC BY-SA 4.0, via Wikimedia Commons.

Estimate first

To estimate, round each number to the nearest hundred, then add or subtract. You learnt rounding in Lesson 4. If your real answer is close to the estimate, it is reasonable.

Worked example 1

Is 3 482 + 2 615 = 6 097 reasonable?

Show me how

3 482 rounds to 3 500. 2 615 rounds to 2 600.

3 500 + 2 600 = 6 100.

6 097 is close to 6 100, so the answer is reasonable.

Watch out! A common mistake

Sam says 4 718 − 1 293 = 2 425. The estimate is 4 700 − 1 300 = 3 400. Sam’s answer is about 1 000 too small, so it cannot be right. The correct answer is 3 425. Do not skip the estimate just because the working looks neat.

Use the inverse

Addition and subtraction are inverse operations: one undoes the other. To check an addition, take one number away from the answer. You should get the other number. To check a subtraction, add your answer to the number you took away. You should get the first number.

Worked example 2

Check 2 768 + 1 459 = 4 227

Show me how

Subtract: 4 227 − 1 459.

4 227 − 1 459 = 2 768.

You got back 2 768, so the addition is right.

Worked example 3

Check 6 004 − 2 378 = 3 626

Show me how

Add: 3 626 + 2 378.

3 626 + 2 378 = 6 004.

You got back 6 004, the number you started with, so the subtraction is right.

Which check should I use?

An estimate is quick and catches big mistakes, like a missing thousand. The inverse takes longer but catches small slips too. If someone says 2 768 + 1 459 = 4 237, the estimate (2 800 + 1 500 = 4 300) looks fine, but the inverse shows 4 237 − 1 459 = 2 778, not 2 768. There is a mistake of 10. In a test, estimate every answer and use the inverse when you have time.

Try it

TRY ITIs it reasonable?

Round to the nearest hundred, judge answers and choose the number sentence that checks a sum.

TRY ITCheck it with the inverse

Someone has worked out a sum. Undo it in columns and see if you get back the number you started with.

Let’s practise

Work out each one in your copybook. Open Hint if you are stuck, then open Show answer to check your working.

1. Estimate 4 386 + 2 517 by rounding to the nearest hundred.

Hint

Round each number first.

Show answer

4 400 + 2 500 = 6 900

2. Estimate 7 812 − 3 274.

Hint

7 812 rounds to 7 800.

Show answer

7 800 − 3 300 = 4 500

3. Is 3 609 + 2 785 = 5 394 reasonable?

Hint

Estimate: 3 600 + 2 800.

Show answer

No. The estimate is 6 400. The answer is 6 394.

4. Write a subtraction to check 1 846 + 2 375 = 4 221.

Hint

Start with the answer.

Show answer

4 221 − 2 375 = 1 846

5. Write an addition to check 8 000 − 3 465 = 4 535.

Hint

Add the answer to the number taken away.

Show answer

4 535 + 3 465 = 8 000

6. Jo says 5 230 − 1 875 = 3 455. Use the inverse to check.

Hint

Work out 3 455 + 1 875.

Show answer

3 455 + 1 875 = 5 330, not 5 230, so Jo is wrong. The answer is 3 355.

7. A shop had 2 450 bottles of juice and got 1 675 more. Kofi says there are now 4 125. Check him two ways.

Hint

Estimate, then use the inverse.

Show answer

Estimate 2 500 + 1 700 = 4 200, close. 4 125 − 1 675 = 2 450. Kofi is right.

8. What should you get when you check 6 318 − 2 904 = 3 414 by adding?

Hint

Add 3 414 and 2 904.

Show answer

6 318

Quiz

Lesson quiz: 10 questions

Answer every question, then press Check my answers. Score 8 or more to earn the Answer Checker badge.

Recap

  • Estimate by rounding each number to the nearest hundred.
  • An answer close to the estimate is reasonable. One far away is wrong.
  • Check addition by subtracting from the answer.
  • Check subtraction by adding the answer to the number taken away.
  • Estimates catch big mistakes. The inverse catches small ones too.

Words to know

estimate
A close guess worked out with rounded numbers.
Example: My estimate for 398 + 205 is 600.
reasonable
Makes sense and is close to the estimate.
Example: 6 097 is a reasonable answer for 3 482 + 2 615.
inverse
The operation that undoes another one.
Example: Subtraction is the inverse of addition.
check
Make sure an answer is right.
Example: I check my sum by subtracting.
exact
Completely correct, not an estimate.
Example: The exact answer is 6 097.

Try it at home

  • At the shop, estimate the total of three items before you pay. Compare your estimate with the bill.
  • Mini project: an adult writes five sums with answers, and gets one or two wrong on purpose. Use estimates and the inverse to find the wrong ones.

Test tips

Tips for class tests

  • Estimate first. If your answer is far from the estimate, work it again.
  • If there is time at the end of a test, check with the inverse.
  • Show the check in your working. Teachers like to see it.

For parents and teachers

After this lesson, your child should be able to:

  • estimate sums and differences by rounding to the nearest hundred;
  • decide if an answer is reasonable;
  • check addition with subtraction and subtraction with addition.

Rounding was taught in Lesson 4 and the column method in Lessons 7 and 8. Praise your child for checking, even when the first answer was right.

Quiz scores and badges are saved only in this browser on this device. Nothing is sent anywhere. If the browser data is cleared, or another device is used, the badges will be lost.

Previous: Subtracting 4-Digit Numbers – Standard 3 Maths
Next: Money Problems: Bills, Best Buy, Profit and Loss – Standard 3 Maths
Course: Standard 3 Maths

Updates

2026/11/04
– First version of this lesson.

Attributions to media used in this post:

Citizen SLD-100NR calculator.jpg – LoMit – CC BY-SA 4.0 (via Wikimedia Commons)

© 2026 Vedesh Kungebeharry. All rights reserved.

Subtracting 4-Digit Numbers – Standard 3 Maths

Aven Brisail1 Comment

What you will learn

  • Subtract numbers with up to four digits using the column method.
  • Regroup (borrow) when the top digit is smaller than the bottom digit.
  • Subtract from numbers with zeros, like 5 000, and solve number stories.

A cricket scoreboard shows how many runs a team still needs. To find that, the scorer subtracts. In this lesson you will subtract numbers up to 9 999 with the column method, one column at a time.

A small wooden cricket scoreboard with white numbers on black boards
A cricket scoreboard. If a team needs 300 runs and has 288, the scorer works out 300 − 288 = 12 more runs. Photo: Acabashi, CC BY-SA 4.0, via Wikimedia Commons.

Top number take away bottom number

Write the bigger number on top and line up the columns. Start with the ones. In each column, take the bottom digit away from the top digit.

Worked example 1

5 786 − 2 341

Show me how

Ones: 6 − 1 = 5. Tens: 8 − 4 = 4.

Hundreds: 7 − 3 = 4. Thousands: 5 − 2 = 3.

The answer is 3 445.

Regrouping

Sometimes the top digit is smaller than the bottom digit. Then you regroup: take 1 from the next column on the left and turn it into 10 in this column. 1 ten becomes 10 ones, 1 hundred becomes 10 tens.

Worked example 2

6 352 − 2 718

Show me how

Ones: you cannot take 8 from 2. Regroup 1 ten: the 5 tens become 4, and 2 ones become 12. 12 − 8 = 4.

Tens: 4 − 1 = 3.

Hundreds: you cannot take 7 from 3. Regroup 1 thousand: 6 becomes 5, and 3 becomes 13. 13 − 7 = 6.

Thousands: 5 − 2 = 3. The answer is 3 634.

Watch out! A common mistake

Do not take the smaller digit from the bigger one just because it is easier. 4 352 − 1 718 is not 3 446. The top number always goes first. Regroup instead: the answer is 2 634.

Zeros and number stories

When the next column is 0, keep going left until you find a digit you can take 1 from.

Worked example 3

5 000 − 1 264

Show me how

You cannot take 4 from 0, and the tens and hundreds are 0 too.

Regroup 1 thousand: 5 becomes 4. The hundreds become 10, then 9 as you pass 1 to the tens. The tens become 10, then 9. The ones become 10.

Ones 10 − 4 = 6, tens 9 − 6 = 3, hundreds 9 − 2 = 7, thousands 4 − 1 = 3. The answer is 3 736.

Words like left, how many more, difference and fewer often tell you to subtract. A ground has 8 500 seats and 6 275 people came: 8 500 − 6 275 = 2 225 empty seats.

Try it

TRY ITColumn subtraction, step by step

Start with the ones. First decide if you can subtract or need to regroup, then tap the digit you write. Regrouped digits show at the top.

Let’s practise

Work out each one in your copybook. Open Hint if you are stuck, then open Show answer to check your working.

1. 7 869 − 3 425

Hint

No regrouping needed.

Show answer

4 444

2. 5 372 − 1 846

Hint

Regroup in the ones and in the hundreds.

Show answer

3 526

3. 8 213 − 4 657

Hint

You regroup three times.

Show answer

3 556

4. 6 000 − 2 485

Hint

Regroup from the thousands, through the zeros.

Show answer

3 515

5. 4 030 − 1 712

Hint

The ones need a ten. The hundreds need a thousand.

Show answer

2 318

6. 9 105 − 678

Hint

Line up the ones: 8 goes under 5.

Show answer

8 427

7. A school raised $5 250 for a trip. The bus costs $3 875. How much money is left?

Hint

Left means subtract.

Show answer

5 250 − 3 875 = 1 375. There is $1 375 left.

8. Kira has 2 340 stickers. Her brother has 1 965. How many more stickers does Kira have?

Hint

How many more means find the difference.

Show answer

2 340 − 1 965 = 375. Kira has 375 more.

Quiz

Lesson quiz: 10 questions

Answer every question, then press Check my answers. Score 8 or more to earn the Regroup Ranger badge.

Recap

  • Write the bigger number on top and line up the columns.
  • Start with the ones and take the bottom digit from the top digit.
  • If the top digit is too small, regroup 1 from the next column into 10.
  • With zeros, keep going left until you find a digit to regroup.
  • Left, how many more and difference often mean subtract.

Words to know

difference
The answer when you subtract.
Example: The difference between 500 and 200 is 300.
regroup
Change 1 ten into 10 ones, or 1 hundred into 10 tens.
Example: I regrouped 1 ten to make 12 ones.
borrow
Another word some people use for regroup.
Example: You borrow from the tens column.
minus
The − sign. It means take away.
Example: 9 minus 4 is 5.
left
What remains after some is taken away.
Example: I had $50, spent $30 and have $20 left.

Try it at home

  • Ask an adult how much something costs and how much money they paid with. Work out the change with the column method.
  • Mini project: find the year you were born and this year. Subtract to find your age. Do the same for two people at home.

Test tips

Tips for class tests

  • Always put the first number in the question on top.
  • Cross out and write the regrouped digit neatly above the column.
  • Check by adding your answer to the bottom number. You should get the top number. Lesson 9 shows you how.

For parents and teachers

After this lesson, your child should be able to:

  • subtract numbers with up to four digits using the column method;
  • regroup, including across zeros such as 5 000 − 1 264;
  • solve and write subtraction stories about money and everyday things.

Many children find zeros hardest. Use the “Numbers with zeros” mode, or model 5 000 as 5 bundles of a thousand that must be opened up. Money in this lesson is in whole dollars, as the guide asks.

Quiz scores and badges are saved only in this browser on this device. Nothing is sent anywhere. If the browser data is cleared, or another device is used, the badges will be lost.

Previous: Adding 4-Digit Numbers – Standard 3 Maths
Next: Checking Answers: Estimation and the Inverse – Standard 3 Maths
Course: Standard 3 Maths

Updates

2026/11/04
– First version of this lesson.

Attributions to media used in this post:

Cricket scoreboard box at Epping Cricket Club, Essex, England 01.jpg – Acabashi – CC BY-SA 4.0 (via Wikimedia Commons)

© 2026 Vedesh Kungebeharry. All rights reserved.

Adding 4-Digit Numbers – Standard 3 Maths

Aven Brisail1 Comment

What you will learn

  • Add numbers with up to four digits using the column method.
  • Carry when a column adds up to 10 or more.
  • Add three or four numbers and solve number stories.

Adding big numbers in your head is hard, but the column method makes it easy. You add one column at a time, starting with the ones. In this lesson you will add numbers up to 9 999, the way you will do it in class tests.

A small wooden abacus with rows of coloured beads on wires
An abacus is an old counting frame. When a row of ten beads is full, you move one bead on the next row instead. That is carrying. Photo: Deinodactyla, CC0, via Wikimedia Commons.

Line up the columns

Write the numbers one under the other so the ones, tens, hundreds and thousands are in straight columns. Start adding on the right, with the ones.

Worked example 1

3 214 + 4 352

Show me how

Ones: 4 + 2 = 6. Tens: 1 + 5 = 6.

Hundreds: 2 + 3 = 5. Thousands: 3 + 4 = 7.

The answer is 7 566. No column made 10 or more, so there was nothing to carry.

Carrying

When a column adds up to 10 or more, you cannot fit it in one place. Write the ones digit and carry the ten to the next column. Ten ones make 1 ten, ten tens make 1 hundred, and ten hundreds make 1 thousand.

Worked example 2

3 456 + 2 189

Show me how

Ones: 6 + 9 = 15. Write 5, carry 1 ten.

Tens: 5 + 8 + 1 = 14. Write 4, carry 1 hundred.

Hundreds: 4 + 1 + 1 = 6. Write 6. Thousands: 3 + 2 = 5.

The answer is 5 645.

Watch out! A common mistake

Do not forget the number you carried. Write it small at the top of the next column, then add it in. Also keep the columns straight: in 2 507 + 86, the 6 goes under the 7, not under the 2.

Three or more numbers and number stories

You can add three or four numbers in the same way. Add every digit in the column, plus anything you carried. Sometimes you carry 2.

Worked example 3

A shop sold 1 275 doubles on Friday, 2 348 on Saturday and 896 on Sunday. How many in all?

Show me how

Write 1 275 + 2 348 + 896 in columns. Ones: 5 + 8 + 6 = 19. Write 9, carry 1.

Tens: 7 + 4 + 9 + 1 = 21. Write 1, carry 2.

Hundreds: 2 + 3 + 8 + 2 = 15. Write 5, carry 1. Thousands: 1 + 2 + 1 = 4.

The shop sold 4 519 doubles.

Words like altogether, in all, total and more often tell you to add. Always write your answer in a sentence.

Try it

TRY ITColumn addition, step by step

Work one column at a time, starting with the ones. Tap the digit you write in the yellow column. Carried digits appear at the top.

Let’s practise

Work out each one in your copybook. Open Hint if you are stuck, then open Show answer to check your working.

1. 2 415 + 3 263

Hint

No carrying needed.

Show answer

5 678

2. 4 527 + 2 345

Hint

Ones: 7 + 5 = 12.

Show answer

6 872 (carry 1 ten)

3. 1 768 + 3 456

Hint

You carry three times.

Show answer

5 224

4. 3 090 + 2 815

Hint

Watch the zeros.

Show answer

5 905

5. 6 342 + 875

Hint

Line up the ones: the 5 goes under the 2.

Show answer

7 217

6. 1 205 + 2 130 + 3 452

Hint

Add three digits in each column.

Show answer

6 787

7. Mr Ali drove 2 486 km in March and 3 158 km in April. How far did he drive in the two months?

Hint

Add the two distances.

Show answer

2 486 + 3 158 = 5 644. He drove 5 644 km.

8. Write your own number story for 1 500 + 2 750, then solve it.

Hint

Use a word like altogether or total.

Show answer

Many stories are possible. The answer is 4 250.

Quiz

Lesson quiz: 10 questions

Answer every question, then press Check my answers. Score 8 or more to earn the Column Adder badge.

Recap

  • Line up ones, tens, hundreds and thousands in columns.
  • Start adding with the ones on the right.
  • If a column makes 10 or more, write the ones digit and carry to the next column.
  • Add three or four numbers the same way.
  • In number stories, words like altogether and total mean add. Answer in a sentence.

Words to know

sum
The answer when you add.
Example: The sum of 2 000 and 500 is 2 500.
column
A line of digits going down, all with the same place value.
Example: The 6 and 9 are in the ones column.
carry
Move a ten to the next column on the left.
Example: 6 + 9 = 15, so write 5 and carry 1.
total
The amount you get when everything is added.
Example: The total number of pupils is 1 240.
altogether
Everything put together.
Example: We sold 300 tickets altogether.

Try it at home

  • Look at a shopping bill or a newspaper. Find two big numbers and add them with the column method. Check with a calculator if an adult has one.
  • Mini project: write three number stories that need adding, one about your school, one about a sport and one about food. Solve each one and ask someone at home to check.

Test tips

Tips for class tests

  • Write the numbers neatly in columns. Use squared paper if you can.
  • Write the carried digit small at the top of the next column so you do not forget it.
  • If the question is a story, underline the numbers and the word that tells you to add.

For parents and teachers

After this lesson, your child should be able to:

  • add numbers with up to four digits, with totals below 10 000, using the column method;
  • carry correctly from the ones, tens and hundreds;
  • add three or four numbers and solve and write number stories.

If your child makes mistakes, use bundles of straws or the place-value builder from Lesson 2 to show why ten ones become one ten. Checking answers is covered in Lesson 9.

Quiz scores and badges are saved only in this browser on this device. Nothing is sent anywhere. If the browser data is cleared, or another device is used, the badges will be lost.

Previous: Number Sentences with a Missing Number – Standard 3 Maths
Next: Subtracting 4-Digit Numbers – Standard 3 Maths
Course: Standard 3 Maths

Updates

2026/11/04
– First version of this lesson.

Attributions to media used in this post:

20th Century Small Wooden Abacus.jpg – Deinodactyla – CC0 1.0 (via Wikimedia Commons)

© 2026 Vedesh Kungebeharry. All rights reserved.

Number Sentences with a Missing Number – Standard 3 Maths

Aven Brisail1 Comment

What you will learn

  • Explain what the equals sign means.
  • Find a missing number using the inverse (opposite) operation.
  • Solve number sentences when the box is on the left or the right of the equals sign.

Some number sentences have a number missing, shown by a box. Finding it is like being a detective: the other numbers are your clues. In this lesson you will learn a trick that works every time: use the opposite operation.

A balance scale with two flat metal pans, level with each other
A balance is level when both sides weigh the same. A number sentence works the same way: both sides of the equals sign have the same value. Photo: Lilly_M, CC BY-SA 3.0, via Wikimedia Commons.

What the equals sign means

A number sentence uses numbers and signs, like 300 + 200 = 500. The equals sign (=) does not mean “the answer comes next”. It means both sides have the same value, like a balance that is level.

So 500 = 300 + 200 and 300 + 200 = 400 + 100 are true number sentences too. When a number is missing, we draw a box: + 200 = 500.

Use the inverse

Adding and subtracting are inverse (opposite) operations. One undoes the other. To find a missing number, do the opposite.

Worked example 1

+ 1 250 = 3 400

Show me how

Something add 1 250 makes 3 400. To undo adding, subtract.

3 400 − 1 250 = 2 150.

Check: 2 150 + 1 250 = 3 400. So = 2 150.

Worked example 2

5 000 − = 1 800

Show me how

5 000 take away something leaves 1 800.

The missing number is the difference: 5 000 − 1 800 = 3 200.

Check: 5 000 − 3 200 = 1 800. So the box is 3 200.

The box can be anywhere

The box can be on the right of the equals sign: 900 = 400 + . It still means the same: 400 and what make 900? The answer is 500.

Sometimes both sides have two numbers: 400 + 300 = + 200. Work out the side you know first: 400 + 300 = 700. Now 700 = + 200, so the box is 500.

Watch out! A common mistake

Do not just add the numbers you can see. In 25 + = 60, the answer is not 85. Ask: 25 and what make 60? 60 − 25 = 35. Always put your answer in the box and check that both sides are equal.

Multiplying and dividing

Multiplying and dividing are inverse operations too. For 7 × = 42, think 42 ÷ 7 = 6. For 42 ÷ = 7, think 7 × 6 = 42, so the box is 6.

Try it

TRY ITBalance the number sentence

Choose a game, then tap the number that goes in the box. If you choose a wrong number, watch the balance tip.

Let’s practise

Work out each one in your copybook. Open Hint if you are stuck, then open Show answer to check your working.

1. + 45 = 120

Hint

What do you add to 45 to make 120?

Show answer

120 − 45 = 75. The box is 75.

2. 2 300 + = 5 000

Hint

Subtract 2 300 from 5 000.

Show answer

5 000 − 2 300 = 2 700.

3. − 350 = 1 650

Hint

Use the inverse: add.

Show answer

1 650 + 350 = 2 000. Check: 2 000 − 350 = 1 650.

4. 6 000 − = 2 500

Hint

How much is taken away?

Show answer

6 000 − 2 500 = 3 500.

5. 800 = 500 +

Hint

The box is on the right. 500 and what make 800?

Show answer

300

6. 350 + 150 = + 100

Hint

Work out the left side first.

Show answer

350 + 150 = 500, and 500 − 100 = 400. The box is 400.

7. (a) 8 × = 56
(b) 63 ÷ = 9

Hint

Use your times tables.

Show answer

(a) 56 ÷ 8 = 7
(b) 9 × 7 = 63, so the box is 7.

8. Ria had some marbles. She won 125 more and now has 400. Write a number sentence with a box, then solve it.

Hint

What did she start with? That is the box.

Show answer

+ 125 = 400. 400 − 125 = 275, so Ria had 275 marbles.

Quiz

Lesson quiz: 10 questions

Answer every question, then press Check my answers. Score 8 or more to earn the Balance Keeper badge.

Recap

  • The equals sign means both sides have the same value.
  • A box stands for a missing number.
  • Use the inverse to find it: subtraction undoes addition, and division undoes multiplication.
  • The box can be on the left or the right of the equals sign.
  • Check by putting your answer in the box: both sides must be equal.

Words to know

number sentence
Numbers and signs that make a statement.
Example: 400 + 100 = 500 is a number sentence.
equals sign
The sign = which means both sides have the same value.
Example: In 6 = 2 + 4 the equals sign is first.
missing number
A number that is not shown, often drawn as a box.
Example: In + 3 = 10 the missing number is 7.
inverse
The opposite operation, which undoes another one.
Example: Subtraction is the inverse of addition.
balance
When both sides are equal.
Example: 300 + 200 and 500 balance.

Try it at home

  • Make a balance with a coat hanger, string and two plastic cups. Put the same number of beans or bottle caps on each side. Take some away from one side and ask someone at home to make it balance again.
  • Mini project: write five missing-number puzzles on cards, with the box in different places. Swap cards with someone at home and check each other’s answers.

Test tips

Tips for class tests

  • Look at the sign first. If it is +, the missing number is usually found by subtracting.
  • Put your answer in the box and work out both sides. They must be equal.
  • If both sides have two numbers, work out the side you know first.

For parents and teachers

After this lesson, your child should be able to:

  • explain that the equals sign means “the same value as”;
  • find a missing number by using the inverse operation;
  • solve number sentences with the box on either side of the equals sign.

Multiplying and dividing here use only facts up to 10 × 10; these are practised fully in the multiplication lessons. Ask your child to check each answer by putting it back in the box.

Quiz scores and badges are saved only in this browser on this device. Nothing is sent anywhere. If the browser data is cleared, or another device is used, the badges will be lost.

Previous: Number Patterns and Rules – Standard 3 Maths
Next: Adding 4-Digit Numbers – Standard 3 Maths
Course: Standard 3 Maths

Updates

2026/11/04
– First version of this lesson.

Attributions to media used in this post:

Simple balance scales-02.jpg – Lilly_M – CC BY-SA 3.0 (via Wikimedia Commons)

© 2026 Vedesh Kungebeharry. All rights reserved.