Math CentralQuandaries & Queries


Question from Amy, a student:

what is the easiest way to remember how to do percents?

Hi Amy.

Just remember that percent means "per hundred" (there are a hundred cents in a dollar right?) That means a fraction.

So 90% means the fraction 90/100.

When you take a percentage of something, you multiply it by that number over 100. For example, the tax on my new computer is 5% of $800. That means I have to pay 800 x 5/100 = $40 tax !

Some people are better with decimals than fractions, and you could certainly use that instead. Just remember that you move the decimal point two places to the left. 90% = 0.90 and 5% = 0.05. Then using the same example as above, 5% of $800 is 800 x 0.05 = $40, just the same.

Use whichever way is easiest for you to remember, but the easiest in my opinion is remembering that "percent" means "per hundred".

Stephen La Rocque.

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