Worked examples
The question
Question: 6 is 50% of what number?
50% of ? = 6
We write it like this: 50% of the number is 6.
6 is a part.
The whole number is what we want.
? = the whole number
Careful!
Many people work out 50% of 6.
But 6 is not the whole.
It is only 50% of it.
Careful: not 50% of 6 ✗
1 Write the percent as a fraction
Percent means out of 100.
So 50% is 50/100.
50% = 50100
50 and 100 can both be divided by 50.
So 50% is 1/2: 1 of 2 equal parts.
= 50 ÷ 50100 ÷ 50 = 12
2 Draw the whole
One part is 6.
So every part is 6.
3 Find the whole
The whole is 2 parts.
2 times 6 is 12.
2 parts = 2 × 6 = 12
So 6 is 50% of 12.
4 Check
Let's check: is 50% of 12 really 6?
50% is 1/2.
Of means times.
12 divided by 2 is 6.
50% of 12 = 12 × 12 = 6 (12 ÷ 2 = 6)
We get 6.
So it is right!
Let's look back.
First: write the percent as a fraction.
Then: draw the whole.
Then: find the whole.
Last: check.
Answer 2 parts = 2 × 6 = 12
▶ Watch it solved
The question
Question: 12 is 30% of what number?
30% of ? = 12
We write it like this: 30% of the number is 12.
12 is a part.
The whole number is what we want.
? = the whole number
Careful!
Many people work out 30% of 12.
But 12 is not the whole.
It is only 30% of it.
Careful: not 30% of 12 ✗
1 Write the percent as a fraction
Percent means out of 100.
So 30% is 30/100.
30% = 30100
30 and 100 can both be divided by 10.
So 30% is 3/10: 3 of 10 equal parts.
= 30 ÷ 10100 ÷ 10 = 310
2 Draw the whole
3 Find one part
3 parts make 12.
So one part is 12 divided by 3.
That is 4.
1 part = 12 ÷ 3 = 4
Every part is 4.
4 Find the whole
The whole is 10 parts.
10 times 4 is 40.
10 parts = 10 × 4 = 40
So 12 is 30% of 40.
5 Check
Let's check: is 30% of 40 really 12?
30% is 3/10.
Of means times.
40 divided by 10 is 4.
3 times 4 is 12.
30% of 40 = 310 × 40 = 3 × 4 = 12 (40 ÷ 10 = 4)
We get 12.
So it is right!
Let's look back.
First: write the percent as a fraction.
Then: draw the whole.
Then: find one part.
Then: find the whole.
Last: check.
Answer 10 parts = 10 × 4 = 40
▶ Watch it solved
The question
Question: 7 is 35% of what number?
35% of ? = 7
We write it like this: 35% of the number is 7.
7 is a part.
The whole number is what we want.
? = the whole number
Careful!
Many people work out 35% of 7.
But 7 is not the whole.
It is only 35% of it.
Careful: not 35% of 7 ✗
1 Write the percent as a fraction
Percent means out of 100.
So 35% is 35/100.
35% = 35100
35 and 100 can both be divided by 5.
So 35% is 7/20: 7 of 20 equal parts.
= 35 ÷ 5100 ÷ 5 = 720
2 Draw the whole
3 Find one part
7 parts make 7.
So one part is 7 divided by 7.
That is 1.
1 part = 7 ÷ 7 = 1
Every part is 1.
4 Find the whole
The whole is 20 parts.
20 times 1 is 20.
20 parts = 20 × 1 = 20
So 7 is 35% of 20.
5 Check
Let's check: is 35% of 20 really 7?
35% is 7/20.
Of means times.
20 divided by 20 is 1.
7 times 1 is 7.
35% of 20 = 720 × 20 = 7 × 1 = 7 (20 ÷ 20 = 1)
We get 7.
So it is right!
Let's look back.
First: write the percent as a fraction.
Then: draw the whole.
Then: find one part.
Then: find the whole.
Last: check.
Answer 20 parts = 20 × 1 = 20
▶ Watch it solved
