Five percentage modes in one place, with the formula printed under every answer.
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This percentage calculator handles the five jobs people actually need: a percent of a number, one number as a percent of another, percent change, percent difference, and a value after a percent rise or fall. Pick a mode, type two numbers, and the formula used is printed under every answer.
Each mode keeps its own labels and its own formula, so a marks question, a price question and a growth question never share the wrong maths.
Percent change needs a direction. It compares a new value with an old one, so swapping the two numbers changes the answer. A rise from 80 to 100 is 25 percent, while a fall from 100 to 80 is 20 percent.
Percent difference has no old and new. It compares two values against their average, so the order does not matter. Two test scores of 80 and 100 differ by about 22.2 percent on this reading.
This page keeps the two apart on purpose. Many wrong answers online come from using the change formula on a difference question, or the other way round.
A percent of a number is the number multiplied by the percent and divided by 100. One number as a percent of another is the first divided by the second, times 100. A value after a rise or fall is the starting value adjusted by that percent of itself.
Some questions have no honest answer, and the tool says so instead of printing a fake figure. Percent change from an old value of zero is one of them, since any rise from nothing cannot be stated as a percent. A percent of a whole of zero fails the same way.
Results are plain arithmetic, with no rounding rules borrowed from exams or tax offices. If a teacher or an accountant needs a set number of decimal places, round the printed answer their way. The calculation itself runs in your browser, with nothing uploaded, no sign-up and no cap on use.
Multiply the number by the percent, then divide by 100. For 20 percent of 250, that is 250 times 20, divided by 100, which gives 50. The first mode on this page does it and prints the formula under the answer.
Change measures movement from an old value to a new one, so order matters. Difference compares two values against their average, so order does not matter. They answer different questions and give different numbers.
Because the starting point changes. Going from 80 to 100 adds 20 on a base of 80, which is 25 percent. Going from 100 to 80 takes 20 off a base of 100, which is 20 percent.
Yes, use the last mode. Type the starting value and the percent, pick rise or fall, and the adjusted value appears with its formula. It works for pay rises, markups and sale prices alike.
Because there is no honest percent for growth from nothing. Dividing by zero has no answer, so the page explains that rather than showing an endless or made up figure.
Divide the first number by the second and multiply by 100. If 45 marks came out of 60, that is 45 divided by 60, times 100, which is 75 percent. The second mode on this page does this.
Same rules as this one: free, in your browser, with nothing uploaded.
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