Understand the idea.
Read the price and unit
A price tells you how much an item costs. Check the money unit before comparing the numbers. When both prices are in dollars, the smaller number is the lower price: a four-dollar notebook costs less than a seven-dollar notebook.
| Item | Price in dollars |
|---|---|
| Plain notebook | 4 |
| Patterned notebook | 7 |
Find the difference
“How much more?” asks for the gap between the prices. Count up from the lower price, or subtract it from the higher price. From four to seven is three dollars. A price comparison tells the cost, but not whether an item suits the job.
See the method in action.
Find a lower price
A red cap costs 9 dollars and a blue cap costs 6 dollars. Which costs less, and by how much?
Worked solution
- 1
Compare the two dollar prices.
Both prices use dollars, and six is the smaller amount.
- 2
Find the gap between the prices.
Subtracting the lower price from the higher price finds how much less.
- 3
Link the difference to the item.
The blue cap has the lower price, so it costs three dollars less.
The blue cap costs 3 dollars less.
Equal prices
Two different rulers each cost 2 dollars. Is one cheaper?
Worked solution
- 1
Compare the prices in the same unit.
Both rulers cost two dollars, even though the rulers are different.
- 2
Check the price difference.
There is no gap between equal prices, so neither ruler is cheaper.
No. They cost the same.
Try it yourself.
Check your understanding
A pencil case costs 8 dollars and a pouch costs 5 dollars. How much more is the pencil case?
Show answer & reasoning
3 dollars.
Both prices are in dollars. The gap is , so the pencil case costs three dollars more.
Keep practising
6 worksheet questions
Read the questions online
- A green pen costs 2 dollars. A purple pen costs 3 dollars. Which costs less?
- A ball costs 12 dollars and a skipping rope costs 9 dollars. Which costs more?
- One book costs 7 dollars and another costs 10 dollars. What is the price difference?
- Two glue sticks each cost 4 dollars. What is the difference in their prices?
- Put these prices in order from lowest to highest: 8 dollars, 3 dollars, 6 dollars.
- A drawing pad costs 6 dollars and a notebook costs 9 dollars. Sam says the notebook costs 15 dollars more. Explain the mistake.
Read the worked solutions
- A green pen costs 2 dollars. A purple pen costs 3 dollars. Which costs less?
2 dollars is less than 3 dollars.
The green pen. - A ball costs 12 dollars and a skipping rope costs 9 dollars. Which costs more?
12 is greater than 9.
The ball. - One book costs 7 dollars and another costs 10 dollars. What is the price difference?
.
3 dollars. - Two glue sticks each cost 4 dollars. What is the difference in their prices?
.
0 dollars. - Put these prices in order from lowest to highest: 8 dollars, 3 dollars, 6 dollars.
Compare the numbers .
3 dollars, 6 dollars, 8 dollars. - A drawing pad costs 6 dollars and a notebook costs 9 dollars. Sam says the notebook costs 15 dollars more. Explain the mistake.
How much more asks for , not .
Sam added the prices. The difference is 3 dollars.
Curriculum reference & lesson scope
Australian Curriculum v9 and SA Curriculum Mathematics
Comparing prices; $1/$2 coins and notes; purchases; limited money and saving; needs/wants; consumer choices.
Official curriculum source ↗