Number
Money & Financial Maths: Understanding Bills, Calculating Change, and Finding Value for Money
3rd Class · 4th Class · 5th Class · 6th Class
- ✓By the end of this lesson students will be able to calculate the total cost of items from a shopping list or bill.
- ✓By the end of this lesson students will be able to accurately calculate the change received after making a purchase.
- ✓By the end of this lesson students will be able to compare prices of different items or quantities to determine which offers better value for money.
- ✓By the end of this lesson students will be able to solve word problems involving money, using correct euro and cent notation.
Key concepts
A bill is a list of items that you have bought or services you have used, along with their individual prices and the total amount you need to pay. When you go shopping, the cashier gives you a receipt, which is a type of bill. It shows what you bought, how much each item cost, and the total cost of your shopping.
When you buy something, you give the shopkeeper money. If the money you give is more than the cost of the item, the shopkeeper gives you back the extra money. This extra money is called 'change'. To calculate change, you subtract the total cost of the items from the amount of money you paid.
Value for money means getting the best quality or quantity for the price you pay. Sometimes, buying a larger pack of an item might seem more expensive, but if you look at the price per item or per unit (like per kilogram or per litre), it might actually be cheaper than buying smaller packs. To find value for money, we often compare the unit price of different options.
Key facts to remember
- 11 euro (€1) is equal to 100 cent (100c).
- 2Money amounts are usually written with a euro sign (€) and two decimal places, e.g., €3.50, not €3.5.
- 3To find the total cost of multiple items, you add their individual prices.
- 4Change is calculated by subtracting the total cost from the amount of money paid (Amount Paid - Total Cost).
- 5To compare value for money, calculate the price per unit (e.g., per item, per kg, per litre).
- 6Always check your change before leaving the shop.
Worked examples
Example 1
Sarah bought a copybook for €1.25, a pencil for €0.70, and a ruler for €1.50. She paid with a €5 note. How much change did she receive?
Answer
Sarah received €1.55 change.
Example 2
A pack of 6 yoghurts costs €3.60. A pack of 4 yoghurts of the same brand costs €2.80. Which pack offers better value for money?
Answer
The pack of 6 yoghurts offers better value for money because each yoghurt costs €0.60, which is cheaper than €0.70 per yoghurt in the 4-pack.
Remember, 'better value for money' usually means a lower price per item or per unit.
Example 3
A family buys 2 loaves of bread at €2.10 each, 3 litres of milk at €1.85 per litre, and 4 apples at €0.65 each. They pay with a €20 note. How much change should they get?
Answer
The family should get €7.65 change.
Break down complex problems into smaller, manageable steps.
Common mistakes
- ✗Forgetting to convert cent to euro or vice versa when adding or subtracting, leading to incorrect totals (e.g., adding 50c to €2 as €2.50 instead of €2.50).
- ✗Making errors in subtraction when calculating change, especially when 'borrowing' across zeros (e.g., €10.00 - €3.45).
- ✗Not multiplying by the correct quantity when an item is bought multiple times (e.g., buying 3 apples but only adding the price of one).
- ✗Confusing the total price of a pack with the unit price when comparing value for money.
- ✗Not showing all steps of working, which can lead to errors and makes it harder to check.
Exam tips
- ★Read each question carefully, highlighting key numbers and what is being asked (e.g., total cost, change, unit price).
- ★Show all your calculations step-by-step. This helps you to keep track of your work and makes it easier to find any mistakes.
- ★Use a calculator if allowed, but always write down the calculation you are performing.
- ★Double-check your answers, especially when dealing with change. You can add the change back to the total cost to see if it equals the amount paid.
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