Percentage of a Number Calculator

Multiply the number by the percentage divided by 100. Fifteen percent of 200 is 200 × 0.15 = 30.

That x% of y equals y% of x. Both are 30 for 15% of 200 and 200% of 15 — and it means 4% of 75 can be worked out as 75% of 4, which is obviously 3.

Divide rather than multiply. If 30 is 15% of a number, the number is 30 ÷ 0.15 = 200.

Going from 10% to 15% is a rise of five percentage points and a rise of 50%. Confusing the two is one of the most common errors in reporting statistics.

Put it over 100 and simplify. Fifteen percent is 15/100, which reduces to 3/20.

Break it into easy parts: 10% is a tenth, 5% is half of that, 1% is a hundredth. Fifteen percent is 10% plus 5%, which most people can do in their head.

Divide the change by the original and multiply by 100. From 40 to 50 is 10 ÷ 40 = 25%, and the base is always the original figure.

Because the base changes. Falling 50% from 100 to 50 requires a 100% rise to get back, since the recovery is measured against the smaller number.

One hundredth of a percentage point, used in finance to remove ambiguity. A rise from 2% to 2.25% is 25 basis points, which cannot be confused with a 25% rise.

The absolute difference between measured and true, divided by the true value, times 100. Using the measured value as the denominator is a common and wrong variant.

Yes, whenever the part exceeds the whole being compared against — 200% of 15 is 30. Only proportions of a fixed whole are capped at 100.

Multiply the total by each share as a decimal, and check that the shares sum to one. Rounding each share separately is what leaves a penny unaccounted for.