Compound measures
Lesson 9 of 9
Best buys
Objective. Compare value for money using unit price.
The key idea
Convert every option to the same unit — price per 100 g or per litre — then the smallest number wins.
Worked example
500 g for £2.40 or 750 g for £3.45. Which is better?
- 1£2.40 ÷ 5 = £0.48 per 100 g.
- 2£3.45 ÷ 7.5 = £0.46 per 100 g.
- 3£0.46 is less.
Answer: The 750 g pack
Practice
Each question comes with a picture and a listen button. Try it first, then reveal the answer.
Common mistake. Assuming the bigger pack is always cheaper per unit.
Your progress
Tick each step as you finish it — Continue brings you back here.
0 of 5 steps complete