Finding percentages of an amount

Mathematics · Ratio & Proportion · ages 10-11

Name ______________________ Date ____________

Find 10% of 360.
Answer: ______________
To find 15% of an amount, which two percentages do you add together?
- 10% and 5%
- 50% and 5%
- 20% and 5%
5% of an amount is always half of 10% of that amount.
Circle one: True False
What is 15% of 200?
- 20
- 30
- 40
For an amount of 360, 10% is 36 and 5% is 18. Use these facts to find 25%.
Answer: ______________
10% of an amount is 16 and 5% is 8. Which calculation finds 35% of that amount?
- 3 × 16 + 16
- 2 × 16 + 8
- 3 × 16 + 8
- 3 × 8 + 16
Find 5% of 360.
Answer: ______________
A $40 shirt has 10% off. A $50 shirt has 20% off. How many dollars larger is the second discount?
Answer: ______________
Ali wants to find 15% of 240. He works out that 10% is 24, then doubles it to get 15%. What mistake did Ali make?
- Doubling 24 gives 20%, not 15%. He should add half of 24 instead of doubling it.
- He should have divided 240 by 15 first.
- He forgot to turn 15% into a fraction before starting.
A bike costs $80 at Shop A with 25% off and $60 at Shop B with 30% off. Which sale price is lower?
- Shop A, for $60
- Shop B, for $42
- Both shops, for $60
- Both shops, for $42

Answer key

For grown-ups. Fold this page away before handing over the rest.

36 · Divide the amount by ten: 360 ÷ 10 = 36.
10% and 5% · 15% breaks neatly into 10% plus 5%, and both of those are easy to work out.
True · 10% split in half gives you 5%, so the amount splits in half too.
30 · 10% of 200 is 20. 5% is half of that: 10. Add them: 20 + 10 = 30.
90 · Twenty-five percent contains two 10% parts and one 5% part: 36 + 36 + 18 = 90.
3 × 16 + 8 · Thirty-five percent contains three 10% parts and one 5% part, giving 3 × 16 + 8 = 56.
18 · Ten percent is thirty-six. Five percent is half that amount, eighteen.
6 · The discounts are four dollars and ten dollars. Their difference is six dollars.
Doubling 24 gives 20%, not 15%. He should add half of 24 instead of doubling it. · Doubling the 10% amount gives you 20%. For 15%, add half of the 10% amount (that is 5%), not double it.
Shop B, for $42 · Shop A charges sixty dollars after its discount. Shop B charges forty-two dollars.