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How to calculate a percentage of a number
Multiply the number by the percentage and divide by 100. 15% of 80 is 80 × 15 ÷ 100 = 12.
Discounts and tips
For a 20% discount on 50, calculate 20% of 50 = 10 and subtract it: 40. For a 15% tip on 80, add 12 to get 92.
Frequently asked questions
How do I find 10% of a number?
Move the decimal point one place to the left.
How do I add a percentage to a number?
Multiply by 1 plus the percentage as a decimal, for example × 1.15 for +15%.
How do I take a percentage off?
Multiply by 1 minus the percentage, for example × 0.80 for −20%.