**Percentages of Whole Numbers** *KS2 Revision*

## What you need to know

** Things to remember:**

- You can add and subtract different percentages to make the percentage you want.

*What is 50% of 80?*

Well, we have a couple of ways of doing this. First, we should look back at how we write percentages as fractions.

Percent Fraction Division

100% \dfrac{1}{1} \div1

50% \dfrac{1}{2} \div2

25% \dfrac{1}{4} \div4

20% \dfrac{1}{5} \div5

10% \dfrac{1}{10} \div10

5% \dfrac{1}{20} \div20

2% \dfrac{1}{50} \div50

1% \dfrac{1}{100} \div100

So, how do we find the 50% of 80? Well, the table tells us we have to divide by 2!

50\% \text{ of }80 = 80\div2=40

Not too bad, right?

*What is 2% of 400?*

The table tells us that to find 2% we have to divide by 50.

2\% of 400 = 400\div50=8

How about if we have to find a percentage that isn’t in our table? Well, we can do that 3 steps.

*What is 35% of 200?*

**Step 1: **Think about what percentages in our table we can add or subtract to make the percentage in the question.

* *

35\% = 25\% + 10\%

**Step 2: **Find these new percentage amounts.

25\% of 200 = 200\div4=50

10\% of 200 = 200\div10=20

**Step 3:** Add or subtract the percentages.

We need to add ours.

35\% = 25\% + 10\%

35\% of 200 = 50 + 20 = 70

Now for the quick and exciting method, which we’d usually do using a calculator.

What is 37% of 400?

What is 37% as a fraction?

37\% = \frac{37}{100}

So, this question can actually be rewritten as:

What is \frac{37}{100} of 400?

But, we know how to do this in two steps:

**Step 1: **Divide the amount by the denominator.

400\div100=4

**Step 2:** Multiply the number in **Step 1** by the numerator.

37\times4=148

37\% of 400 = 148

So, we can actually use these steps to find ANY percentage amount, even decimals!

What is 59 % of 300?

**Step 1: **Divide the amount by 100.

300\div100=3

**Step 2:** Multiply by your percentage.

3\times59=177

59\% of 300 = 177

## Example Questions

**Question 1:** What is 45% of 40?

**Step 1: **Think about what percentages in our table we can add or subtract to make the percentage in the question.

** **45\% = 50\% - 5\%

**Step 2: **Find these new percentage amounts.

50\% of 40 = 40\div2=20

5\% of 40 = 40\div20=2

**Step 3:** Add or subtract the percentages.

We need to add ours.

45\% = 50\% - 5\%

45\% of 40 = 20 -2 = 18

**Question 2:** What is 87% of 700?

*Hint: **Try using a calculator*

**Step 1: **Divide the amount by 100.

700\div100=7

**Step 2:** Multiply by your percentage.

7\times87=609

87\% \text{ of } 700 = 609