Percentage Calculator

X percent of Y = (X / 100) x Y. X as a percent of Y = (X / Y) x 100. Y increased by X percent = Y x (1 + X / 100), and decreased is Y x (1 - X / 100).

How do I work out a percentage of a number in my head?

Find 10 percent by moving the decimal one place, then build from it. 15 percent of 240 is 24 plus half of 24, which is 36. It works for most everyday percentages.

Why is adding 20 percent then removing 20 percent not the original number?

Because the second percentage is taken from a larger number. 100 plus 20 percent is 120, and 20 percent of 120 is 24, so you land on 96. To reverse a 20 percent increase you divide by 1.2, not subtract 20 percent.

What is the difference between percent and percentage points?

A rate going from 4 percent to 5 percent has risen by one percentage point, but by 25 percent. Both are correct and they mean very different things, which is why the distinction gets used carefully in finance.