Maths hiding in shopping: change at the till

Quick answer

When you buy something, the till gives you back the difference between what you paid and what the item cost. This is your change. You can work out change by counting up from the price to the amount paid, or by subtracting the price from the amount paid.

Learning outcome

By the end of this page, you will be able to work out how much change you should get when shopping, using counting up or subtraction methods.

• You can count up from the price to the amount paid to find change
• You can use subtraction to find change
• You can use real money or pretend money to practice
• You can explain how you worked out your change to a friend

Why this matters

Shopping maths is all around us, and understanding how to work out change helps you become confident with money and numbers. Whether you're buying a snack, a toy, or a big treat, knowing how to calculate change means you can check if the till has given you the right amount. It's also a great way to practice subtraction and addition!

How it works

When you buy something, you give the till some money. The till tells you how much the item costs. The difference between what you gave and what the item cost is your change. There are two ways to work this out:

1. Counting up: Start from the price and count up to the amount you gave.
2. Subtraction: Subtract the price from the amount you gave.

Let’s look at how these work in practice.

Examples you can see

Imagine you buy a chocolate bar that costs 65p and you give the till £1. Let’s work out your change using both methods.

Method 1: Counting up

Start from 65p and count up to £1 (which is 100p):

• 65p to 70p = 5p
• 70p to 80p = 10p
• 80p to 90p = 10p
• 90p to 100p = 10p

Now add up the amounts you counted: 5p + 10p + 10p + 10p = 35p

Your change is 35p.

Method 2: Subtraction

Subtract the price from the amount you gave:

£1.00 - 65p = 35p

Your change is 35p.

Real-world example: A trip to the toy shop

Sarah wants to buy a toy that costs £2.40. She gives the shopkeeper £5. How much change should she get?

Using counting up:

• 2.40 to 2.50 = 10p
• 2.50 to 3.00 = 50p
• 3.00 to 5.00 = £2.00

Add these amounts: 10p + 50p + £2.00 = £2.60

Sarah gets £2.60 in change.

Another example: Buying snacks

Tommy buys a sandwich for £1.80 and a drink for 75p. He gives the till £5. How much change does he get?

First, find the total cost:

£1.80 + 75p = £2.55

Now, work out the change:

£5.00 - £2.55 = £2.45

Tommy gets £2.45 in change.

Try it as a mini adventure

Imagine you are a shopkeeper and a customer wants to buy a book that costs £3.20. The customer gives you a £5 note. What change should you give back?

Let’s work it out together:

1. Start from £3.20
2. Count up to £5.00
3. First, go to £3.50 = 30p
4. Then, to £4.00 = 50p
5. Then, to £5.00 = £1.00
6. Add the amounts: 30p + 50p + £1.00 = £1.80

You should give back £1.80.

Now, try it yourself! Pretend you're the customer and the shopkeeper. Swap roles and practice with different prices and amounts.

Common mistakes

• Mistake: Forgetting to subtract or count up to the correct amount.
• Why it happens: Getting confused about whether to count up or subtract.
• Fix: Use both methods to double-check your answer.
• Mistake: Adding the price and the change together instead of subtracting.
• Why it happens: Confusing the relationship between the two numbers.
• Fix: Remember that change is what's left after paying for the item.
• Mistake: Misreading the price, especially with pence.
• Why it happens: Not reading the price carefully or confusing £ and p.
• Fix: Always read the price twice and check that it makes sense.

Parent and carer guide

Shopping is a great place to practice maths! Here are 5 ways you can help your child at home:

1. Practice with real money: Use real coins and notes to make pretend purchases and calculate change.
2. Ask questions: "How much change will you get?" or "If you had £2 and the item cost 65p, how much would you get back?"
3. Use a calculator: Let your child use a calculator to check their answer after they've calculated it themselves.
4. Make it fun: Turn shopping into a game by giving challenges like "Can you find the item that costs exactly £1.50?"
5. Don’t rush: Allow your child to take their time and explain their thinking. This builds confidence and understanding.

Practice questions

1. You buy a pencil for 45p and give the till 50p. How much change do you get?
2. A toy costs £2.10. You pay with £5. How much change do you get?
3. You buy a bottle of juice for 80p and pay with £1. How much change do you get?
4. A book costs £3.75. You pay with £10. How much change do you get?
5. You buy a bag of crisps for 65p and give £1. How much change do you get?

Answers:

1. 5p
2. £2.90
3. 20p
4. £6.25
5. 35p

FAQ

Why do I need to know how to work out change?

Knowing how to work out change helps you be confident with money, makes shopping easier, and builds your skills for bigger maths problems in school.

Can I use a calculator to work out change?

Yes! Using a calculator is a great way to check your answer, but it's also good to practice doing it by hand first.

What if I get the wrong change?

If you think you've been given the wrong amount, always double-check your change or ask the shopkeeper to count it again.

Is counting up or subtracting better?

Both methods work! Some children find counting up easier, others prefer subtracting. Try both and see which you like best.

How can I practice change at home?

You can use play money, make up pretend shops, or ask your child to calculate change for items in a shop.