Shopping Maths
Unit Prices maths mission
A junior real-world challenge using unit prices to practise division without feeling like a worksheet.
Quick answer
Unit prices help you find the best value when shopping by comparing how much each item costs per unit – like how much each apple costs, or how much each litre of milk costs. You work out unit prices by dividing the total price by the number of units.Learning outcome
By the end of this page, you will be able to compare unit prices to find the best value when shopping, using division to work out how much each item costs per unit. Success signs:- You can divide a total price by the number of items to find the unit price
- You can compare unit prices to choose the best deal
- You can explain why one item is better value than another
- You can use unit prices to save money when shopping
Why this matters
Unit prices help you make smart shopping choices. When you're buying groceries, toys, or anything else, knowing the unit price helps you save money and get the best deal. It's like being a detective – you look at the numbers and find the cheapest option. This skill helps you become a smart shopper and makes your money go further. You’ll use this skill in real life when you go shopping with your family or when you get pocket money to spend.How it works
To find the unit price, you divide the total price by the number of items or the amount you are buying. For example, if you buy 5 apples for £2.50, you work out how much one apple costs by dividing £2.50 by 5. The unit price is £0.50 per apple. You can compare this with other apples to see which is the best value. Step-by-step:- Look at the total price of the item
- Look at how many units are in the pack (like 5 apples or 1 litre)
- Divide the total price by the number of units
- Compare unit prices to find the best deal
Examples you can see
Let’s imagine you are at the shop and want to buy some juice. You see two bottles: Bottle A: 1 litre for £1.20 Bottle B: 500 ml for £0.70 To find the unit price, you divide the total price by the number of millilitres or litres. For Bottle A: £1.20 ÷ 1 litre = £1.20 per litre For Bottle B: £0.70 ÷ 0.5 litres = £1.40 per litre So, Bottle A is better value because it costs less per litre. Another example: You are buying pencils. Pack 1: 10 pencils for £2.00 Pack 2: 5 pencils for £1.00 For Pack 1: £2.00 ÷ 10 pencils = £0.20 per pencil For Pack 2: £1.00 ÷ 5 pencils = £0.20 per pencil They are the same value – both cost £0.20 per pencil.Try it as a mini adventure
The Shopping Detective Mission You are a detective on a mission to find the best value for your money! You have £5 to spend on snacks for a party. You must choose the best deals from these options: 1. Chips: 200g for £1.50 2. Chocolate bars: 10 bars for £4.00 3. Cookies: 50 cookies for £3.00 4. Popcorn: 300g for £2.40 Your mission: 1st time: Calculate the unit price for chips (200g) 2nd time: Calculate the unit price for chocolate bars (10 bars) 3rd time: Calculate the unit price for cookies (50 cookies) 4th time: Calculate the unit price for popcorn (300g) 5th time: Decide which snack gives the most for your £5 Let’s start with chips: £1.50 ÷ 200g = £0.0075 per gram That’s 7.5p per gram. Can you work out the rest?Common mistakes
- Mistake: Thinking that the most expensive item is always the best value. Why it happens: Children might not understand that more money doesn’t always mean better value. Fix: Always calculate the unit price to compare fairly.
- Mistake: Forgetting to convert units (like grams to kilograms) when comparing. Why it happens: Children might not know that 1000g = 1kg. Fix: Make sure all units are the same before dividing.
- Mistake: Adding prices instead of dividing. Why it happens: Children might mix up operations. Fix: Remember: to find unit price, you divide the total price by the number of units.
- Mistake: Not checking if the unit prices are the same. Why it happens: Children may rush through calculations. Fix: Always double-check your division.
Parent and carer guide
Parents and carers can help by:- Playing a shopping game at home using real prices from a supermarket flyer or online
- Using unit prices to decide which pack of cereal, snacks, or drinks is the best value
- Encouraging children to explain their thinking when calculating unit prices
- Practising division with everyday items like 12 cookies shared between 4 people
- Letting children use a calculator to check their work, but not to avoid learning the steps
- "Let’s work out how much each apple costs."
- "Which one is the better deal? Why?"
- "Can you show me how you worked out the unit price?"
- "How much would 10 apples cost if one costs 50p?"
- It’s okay if they make a mistake – that’s how you learn!
- Don’t worry if they need help with the division – you can do it together
- Unit prices can be tricky, but with practice, it gets easier
Practice questions
- 12 eggs cost £2.40. What is the unit price per egg? Answer: £0.20 per egg
- 500g of cheese costs £3.00. What is the unit price per 100g? Answer: £0.60 per 100g
- 3 bottles of juice cost £4.50. What is the unit price per bottle? Answer: £1.50 per bottle
- 100g of chocolate costs £1.20. What is the unit price per 100g? Answer: £1.20 per 100g
- 8 packets of crisps cost £2.00. What is the unit price per packet? Answer: £0.25 per packet
FAQ
What is a unit price?
A unit price is how much something costs per unit, like per litre, per kilogram, or per item. It helps you compare prices fairly.
Why do we need to know unit prices?
Unit prices help you save money by choosing the best value deal when shopping.
Can I use a calculator for unit prices?
Yes, you can use a calculator to check your work, but it's good to practice the division first.
How do I know which unit to use?
Look at the packaging. If it says 500g, use grams. If it says 1 litre, use litres. Always make sure units are the same when comparing.
What if the prices are in pence?
You can still divide the total price by the number of units. Just remember to convert pence to pounds if needed (e.g. 50p = £0.50).