**Percentages of Money** *KS3 Revision*

## What you need to know

**Things to remember:**

- We can find a percentage amount by breaking it up into smaller percentages and adding/subtracting/dividing, or by finding 1% and multiplying.
- When writing money, we write it to 2dp. So, we may need to add an extra decimal or round.

* *

Before we start, it is worth remembering some simple percentage conversions:

Percentage Division

100% \div1

50% \div2

25% \div4

20% \div5

10% \div10

5% \div20

4% \div25

2% \div50

1% \div100

Finding percentage amounts of money is the same as finding amounts of just normal numbers, which we learn two methods for in **Comparing Percentages**.

*What is 30% of £82?*

We’ll use **Method 1** from **Comparing Percentages**.

**Step 1:** Think about the percentages that add or multiply together to make your percentage.

** **

30\%=20\%+10\%

** **

**Step 2: **Find the value of these percentages

20\%\text{ of }\pounds 82 = \pounds 82\div5=\pounds 16.4

10\%\text{ of } \pounds 82 = \pounds 82\div10=\pounds 8.2

**Step 3:** Add/Subtract/Multiply

30\%=20\%+10\%

30\%\text{ of } \pounds82=\pounds 16.4+\pounds 8.2=\pounds 24.6

But, we have to remember that when we have money it comes in 2dp, so the answer is £24.60.

*What is 89.5% of £15?*

* *

We’ll use **Method 2 **from **Comparing Percentages**.

**Step 1: **Divide the number you’re finding the percentage of by 100 to find 1%.

** **

15\div100=0.15

1\%=0.15

** **

**Step 2:** Multiply the value of 1% found in Step 1 by your starting percentage.

89.5\%=89.5\times1\%

89.5\%\text{ of }15=89.5\times0.15=13.425

So, this time, our answer is £13.425. But, now we have too many decimal places, so we need to round it so we only have two. Our answer this time will be £13.43.

## Example Questions

**Question 1:** What is 29% of £26?

**Method 1**

**Step 1:** Think about the percentages that add or multiply together to make your percentage.

** **

29\%=25\%+5\%-1\%

**Step 2: **Find the value of these percentages

25\%\text{ of }26=26\div4=6.5

5\%\text{ of }26=26\div20=1.3

1\%\text{ of }26=26\div100=0.26

**Step 3:** Add/Subtract/Multiply

29\%=25\%+5\%-1\%

29\%\text{ of }24=6.5+1.3-0.26=7.54

29% of £26 is £7.54.

**Method 2**

**Step 1: **Divide the number you’re finding the percentage of by 100 to find 1%.

** **

26\div100=0.26

1\%=0.26

** **

**Step 2:** Multiply the value of 1% found in Step 1 by your starting percentage.

29\%=29\times1\%

29\%\text{ of }26=29\times0.26=7.54

29% of £26 is £7.54.

**Question 2:** What is 18% of £35?

**Method 1**

**Step 1:** Think about the percentages that add or multiply together to make your percentage.

** **

18\%=20\%-2\%

**Step 2: **Find the value of these percentages

20\%\text{ of }35=35\div5=7

2\%\text{ of }35=35\div50=0.7

**Step 3:** Add/Subtract/Multiply

18\%=20\%-2\%

18\%\text{ of }35=7-0.7=6.3

*Hint: **Remember, we have to have two decimal places.*

18% of £35 is £6.30.

**Method 2**

**Step 1: **Divide the number you’re finding the percentage of by 100 to find 1%.

** **

35\div100=0.35

1\%=0.35

** **

**Step 2:** Multiply the value of 1% found in Step 1 by your starting percentage.

18\%=18\times1\%

18\%\text{ of }35=18\times0.35=6.3

*Hint: **Remember, we have to have two decimal places.*

18% of £35 is £6.30.