Percent of a Number
Also known as what is 15 percent of · percentage of a number · part rate whole · find the percentage · x percent of y · percentage calculator · how much is 20 percent of · is what percent of
Worked example: 15 % of 240 → 36 — press Try an example to run it live, then adjust anything.
Enter your known values, leave one input blank, and solves for the missing one. Tap a variable’s symbol to see what it means, with a typical value. Try different units for next level excitement!
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Percent means per hundred, and that is the whole idea: a rate of 15 % is the fraction , and the part is that fraction of the whole. The word arrived through Italian merchants' per cento and the sign itself is a worn-down abbreviation of it, the c and the o having collapsed into the two little circles over three centuries of hurried bookkeeping.
Three questions live in one equation, and school arithmetic gives them three different names as though they were three topics. What is 15 % of 240 solves for the part. What percent of 180 is 45 solves for the rate. 30 is 12 % of what number solves for the whole. They are the same line read from three directions, which is why this page has three brains rather than three pages.
Two habits are worth building. First, sanity-check against the easy anchors: 10 % is the decimal point moved one place, 50 % is half, 25 % is half of half, and almost any percentage can be assembled from those in your head. Second, remember that percentages of different wholes cannot be added. A 20 % rise followed by a 20 % fall does not return you to where you started, because the second 20 % is taken from a bigger number than the first was added to — you end at 96 % of the original. That single fact is behind more bad arithmetic in the news than any other.
- = Part
- = Rate
- = Whole