90% as a fraction
Per cent means out of 100: 90% is 90/100, which simplifies to 9/10.
The answer
90% = 9/10
How to write 90% as a fraction
Per cent means out of 100, so write the percentage over 100: 90% = 90/100.
Simplify by dividing the top and bottom by the same number. In one go, divide by the highest common factor, 10: 90/100 = 9/10.
9 and 10 share no factor except 1, so 9/10 is the simplest form.
As a decimal, 90% = 0.9: divide by 100, which moves each digit two places to the right.
To check, divide back: see 9/10 as a decimal and 9/10 as a percentage.
Using 9/10 to find 90% of an amount
Knowing that 90% is 9/10 makes finding 90% of an amount quick: divide by 10 to find 1/10, then multiply by 9.
90% of 40 = 40 ÷ 10 × 9 = 4 × 9 = 36
The bar model below opens on 90% of 40 and reaches the same answer another way, by building 90% from 50% and 40%. Change the numbers to try your own.
A bar model that finds a percentage of any amount, step by step. 90% of 40 is 36.
See 9/10
More percentages as fractions
Questions parents ask
What is 90% as a fraction?
90% = 90/100 = 9/10 in its simplest form.
What is 90% as a decimal?
90% = 0.9. Divide by 100: the digits move two places to the right.
How do you find 90% of an amount?
90% is 9/10, so divide by 10, then multiply by 9. For 90% of 40: 40 ÷ 10 = 4, and 4 × 9 = 36.
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