How to use it
- Pick the line that matches your question.
- Type the numbers; the result appears immediately.
- Use the last line for discounts, taxes or tips: it shows the number with the percent added and removed.
Questions and answers
How do I calculate X% of a number?
Multiply the number by X and divide by 100. For example, 15% of 200 = 200 × 15 ÷ 100 = 30.
How do I calculate a percentage increase?
Subtract the old value from the new one, divide by the old value and multiply by 100. From 80 to 100 is (100 − 80) ÷ 80 × 100 = 25% more.
How do I take a discount off a price?
Multiply the price by (1 − discount ÷ 100). A 10% discount on 250 is 250 × 0.9 = 225. The last line of the calculator does this for you.