Understand the idea.
Make a small purchase plan
Start a purchase plan by listing what is bought and the price of each item. Add prices for different items. For several items at the same price, multiplication counts the equal groups.
Use cents for every amount before calculating: one dollar and twenty cents is cents. An estimate is a useful check. Three items at about half a dollar each should cost about one and a half dollars.
| Item | Price |
|---|---|
| Bookmark | 50 cents |
| Pencil | 85 cents |
| Eraser | 40 cents |
Check the money and change
Compare the total cost with the money available. If the cost is greater, the money cannot pay for the whole plan. If the cost is equal, you can pay exactly and receive no change.
When you pay more than the cost, the change is the difference. Subtract the cost from the amount paid. Then add cost and change to check that they rebuild the payment.
See the method in action.
Several identical items
Buy 3 bookmarks at 50 cents each. Pay with 2 dollars. What change should you receive?
Worked solution
- 1
Find the cost of three bookmarks.
Each bookmark has the same 50-cent price.
- 2
Write the payment in cents.
Cost and payment must use the same unit.
- 3
Subtract the cost.
The payment is enough, and the difference is the change.
- 4
Check the change.
The cost and returned money must equal the amount paid.
50 cents change.
Different items
A pencil costs 85 cents and an eraser costs 40 cents. Find the total and the change from 2 dollars.
Worked solution
- 1
Add the two prices.
Buying one of each item means joining both costs.
- 2
Name the total in dollars and cents.
100 cents form one whole dollar.
- 3
Subtract from the payment.
Two dollars pay the 125-cent cost and leave this change.
- 4
Check the payment.
Cost plus change returns to the original two dollars.
Total 1 dollar 25 cents; change 75 cents.
Try it yourself.
Check your understanding
Two items cost 60 cents each. Are 2 dollars enough? What change remains?
Show answer & reasoning
Yes; 80 cents change.
Two items cost cents. Two dollars are cents, which is enough. The change is cents.
Keep practising
6 worksheet questions
Read the questions online
- A sticker costs 20 cents. What do 4 stickers cost?
- A notepad costs 1 dollar 20 cents. A pencil costs 50 cents. Find the total.
- A bookmark costs 75 cents. Find the change from 1 dollar.
- Two folders cost 1 dollar each. Can 1 dollar 80 cents pay for both?
- A child buys an 80-cent pen and a 35-cent eraser. They pay 2 dollars and receive 85 cents change. Check the change.
- You have 2 dollars. Cards cost 60 cents each. What is the greatest number you can buy, and what money remains?
Read the worked solutions
- A sticker costs 20 cents. What do 4 stickers cost?
.
80 cents. - A notepad costs 1 dollar 20 cents. A pencil costs 50 cents. Find the total.
cents.
1 dollar 70 cents. - A bookmark costs 75 cents. Find the change from 1 dollar.
cents.
25 cents. - Two folders cost 1 dollar each. Can 1 dollar 80 cents pay for both?
Both cost 200 cents. cents.
No; it is 20 cents short. - A child buys an 80-cent pen and a 35-cent eraser. They pay 2 dollars and receive 85 cents change. Check the change.
cents; cents.
It is correct. - You have 2 dollars. Cards cost 60 cents each. What is the greatest number you can buy, and what money remains?
cents; . Four cost 240 cents, which is too much.
3 cards, with 20 cents remaining.
Curriculum reference & lesson scope
Australian Curriculum v9 and SA Curriculum Mathematics
Dollars/cents; equivalent amounts; modelling purchases; needs/wants; class enterprise and others' wellbeing.
Official curriculum source ↗