Step by step
The question
Question: 63 is 90% of what number?
90% of ? = 63
We write it like this: 90% of the number is 63.
63 is a part.
The whole number is what we want.
? = the whole number
Careful!
Many people work out 90% of 63.
But 63 is not the whole.
It is only 90% of it.
Careful: not 90% of 63 ✗
1 Write the percent as a fraction
Percent means out of 100.
So 90% is 90/100.
90% = 90100
90 and 100 can both be divided by 10.
So 90% is 9/10: 9 of 10 equal parts.
= 90 ÷ 10100 ÷ 10 = 910
2 Draw the whole
3 Find one part
9 parts make 63.
So one part is 63 divided by 9.
That is 7.
1 part = 63 ÷ 9 = 7
Every part is 7.
4 Find the whole
The whole is 10 parts.
10 times 7 is 70.
10 parts = 10 × 7 = 70
So 63 is 90% of 70.
5 Check
Let's check: is 90% of 70 really 63?
90% is 9/10.
Of means times.
70 divided by 10 is 7.
9 times 7 is 63.
90% of 70 = 910 × 70 = 9 × 7 = 63 (70 ÷ 10 = 7)
We get 63.
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 × 7 = 70