How to Quickly Calculate Percentages – Scientific American

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How to calculate percentages is easier than you think. Quick, what’s 36% of 25? Or how about 250% of 20? Learn a quick and dirty tip to help you calculate all of those pesky percentages in your head.

How to calculate percentages can be easier than you may realize. Keep reading for some simple tricks.
Long time math fans may remember our first foray into the world of percentages way back in the 12th and 13th episodes of the podcast. In those shows we learned what percentages are, how they’re related to fractions, how to use percentages to easily calculate tips at restaurants, and how to use percentages to easily calculate sales prices when shopping.
If you’re not sure how to perform any of those handy calculations, or if you’re just in need of a general percentage refresher, I highly recommend taking a look at those earlier shows and getting yourself up to speed. Why? Because once you’re caught up, you’ll be ready to step up and learn how to become a true percentage-calculating machine. Which is exactly what we’re going to turn you into today.
Jason Marshall, PhD, is a research scientist, author of The Math Dude’s Quick and Dirty Guide to Algebra, and host of the Math Dude podcast on Quick and Dirty Tips.
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