Life skills · Grades 4–8
Unit prices and practical comparisons
Use a unit price when package sizes differ.
Understand the idea
Compare equal quantities
Use a unit price when package sizes differ.
Include constraints
The cheapest per unit is not always usable within a budget or before waste occurs.
Use the stated prices
All prices here are fictional arithmetic examples with no tax unless stated.
Worked examples
A 600 g bag costs 3.60 units. Find its price per 100 g.
3.60/6 = 0.60.
0.6
Which has the lower price per item: 4 pencils for 2.00 units or 6 for 3.60 units?
The unit prices are 0.50 and 0.60.
4 pencils for 2.00 units
Try it yourself
A 2 L bottle costs 4.20 units. Find the price per litre.
Why might a large pack with a lower unit price still be a poor choice for one person?
A 15-unit item has a 20% discount. Find the discount amount.
An order costs 18 units plus a 4-unit delivery fee. Find the total.
Answers and marking notes
Answers and marking notes
- 2.1
4.20/2 = 2.10.
- It may exceed the budget or contain more than can be used, creating waste or storage problems.
Credit a practical constraint.
- 3
0.20 × 15 = 3.
- 22
18 + 4 = 22.
Preview material · independent educational review required. Grade bands are approximate, not official curriculum alignment.