80% as a fraction
Per cent means out of 100: 80% is 80/100, which simplifies to 4/5.
The answer
80% = 4/5
How to write 80% as a fraction
Per cent means out of 100, so write the percentage over 100: 80% = 80/100.
Simplify by dividing the top and bottom by the same number. In one go, divide by the highest common factor, 20: 80/100 = 4/5.
If you cannot spot 20, smaller steps get there too:
- Divide by 10: 8/10
- Divide by 2: 4/5
4 and 5 share no factor except 1, so 4/5 is the simplest form.
As a decimal, 80% = 0.8: divide by 100, which moves each digit two places to the right.
To check, divide back: see 4/5 as a decimal and 4/5 as a percentage.
Using 4/5 to find 80% of an amount
Knowing that 80% is 4/5 makes finding 80% of an amount quick: divide by 5 to find 1/5, then multiply by 4.
80% of 40 = 40 ÷ 5 × 4 = 8 × 4 = 32
The bar model below opens on 80% of 40 and reaches the same answer another way, by building 80% from 50% and 30%. Change the numbers to try your own.
A bar model that finds a percentage of any amount, step by step. 80% of 40 is 32.
See 4/5
More percentages as fractions
Questions parents ask
What is 80% as a fraction?
80% = 80/100 = 4/5 in its simplest form.
What is 80% as a decimal?
80% = 0.8. Divide by 100: the digits move two places to the right.
How do you find 80% of an amount?
80% is 4/5, so divide by 5, then multiply by 4. For 80% of 40: 40 ÷ 5 = 8, and 8 × 4 = 32.
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