Steply

40% of a number is 26. Work out the number.

Step by step, with the reason for every step · GCSE Maths Foundation Paper 2 · GCSE Maths

Step by step

The question

Question: 26 is 40% of what number?

40% of ? = 26

We write it like this: 40% of the number is 26.

26 is a part.

The whole number is what we want.

? = the whole number

Careful!

Many people work out 40% of 26.

But 26 is not the whole.

It is only 40% of it.

Careful: not 40% of 26 ✗

1 Write the percent as a fraction

Percent means out of 100.

So 40% is 40/100.

40% = 40100

To make it simpler: What goes into 40 and 100?

We list the numbers that go into each.

Into 40: 1, 2, 4, 5, 8, 10, 20, 40.

Into 100: 1, 2, 4, 5, 10, 20, 25, 50, 100.

20 is the biggest one in both lists.

Into 40: 1, 2, 4, 5, 8, 10, 20, 40
Into 100: 1, 2, 4, 5, 10, 20, 25, 50, 100

We divide the top and the bottom by 20.

So 40% is 2/5: 2 of 5 equal parts.

= 40 ÷ 20100 ÷ 20 = 25

2 Find one part

2 parts make 26.

So one part is 26 divided by 2.

That is 13.

1 part = 26 ÷ 2 = 13

3 Find the whole

The whole is 5 parts.

5 times 13 is 65.

5 parts = 5 × 13 = 65

So 26 is 40% of 65.

4 Check

Let's check: is 40% of 65 really 26?

40% is 2/5.

Of means times.

65 divided by 5 is 13.

2 times 13 is 26.

40% of 65 = 25 × 65 = 2 × 13 = 26 (65 ÷ 5 = 13)

We get 26.

So it is right!

Let's look back.

First: write the percent as a fraction.

Then: find one part.

Then: find the whole.

Last: check.

Answer
5 parts = 5 × 13 = 65

Your turn

Try this one yourself, then check your answer:

40% of what number is 30?
Show the answer
75

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