Complete the questions below in the back of your book.
Examples - these are to help, don't write these in your books.
Finding 20% of 80
Let's start by working out 10% of 80
10% of 80 = 80 ÷ 10 = 8
Now working out 20% is easy:
20% = 10% + 10% = 8 + 8 = 16
Let’s try look at a harder example
Find 35% of 60
Let’s start again by working out 10%
10% of 60 = 60 ÷ 10 = 6
Now work out 5% - 5% is half 10% so we can divide our answer for 10% by 2
5% = 6 ÷ 2 = 3
Now working out 35% is easy:
35% = 10% + 10% + 10% + 5% = 6 + 6 + 6 + 3 = 21
Questions - make sure you show all your working out!
- 10% of 70
- 15% of 30
- 35% of 80
- 60% of 90
- 55% of 40
- 11% of 120 (remember to find 1% divide by 100)
- 15% of 70
- 20% of 62
- 51% of 120
- In a school of 400 pupils, 53% are boys, how many pupils are boys?
- A new born baby's body is 75% water. If a new born baby weighs 3000g, how many grams of water does it contain?
- David had £230 before spending 20% of his money on clothes, how much does he have now?
- 82% of 150 students passed their maths test, how many passed?
- 30% of 140 students in a year said maths was their favourite subject, how many students did NOT say maths was their favourite subject?
Extension Questions
- Work out 0.1% of 56
- Which is greater: 12% of 15 or 8% of 20?
