# Everyday Calculation

Free calculators and unit converters for general and everyday use.

Calculators » Math » Percentage

## Percentage Calculator

Our online tools will provide quick answers to your calculation and conversion needs. On this page, you can calculate percentages 3-way and get answers to the following: what percent of a is b?, what is a percent of b?, and a is b percent of what number?

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#### Percentage formula

In mathematics, a percentage is a number or ratio expressed as a fraction of 100. i.e., 5% = 5/100 = .05.

So, x% of y = x/100 × y

See the sample calculations to learn how to work out percentages.

#### Sample percentage problems

1. What is 40% of 600?

Ans. Since 40% = 40/100,
Therefore, 40% of 600 = 40/100 × 600 = .4 × 600 = 240

2. What percent is 40 of 800?

Ans. Since we have to find the percentage, we write down the problem as:
x% of 800 = 40
x/100 × 800 = 40
x × 800 = 40 × 100
x = 40 × 100 / 800
x = 5 or x% = 5%

3. 12 is 20% of what amount?

Ans. Writing the problem as a percentage equation, we have:
20% × x = 12
20/100 × x = 12
⇒ 20 × x = 12 × 100
x = 12 × 100/20
x = 60