Percents

Finding how much a percent is worth

Let's imagine you scored 85% on your driving test. There were 20 questions on the test, and you want to figure out how many of them you got right. You just learned how to set up this example—now you'll learn how to solve it.

Click through the slideshow to learn how to find how much a percent is worth.

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  Before we start solving, let's set up our example as a mathematical expression.

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  We'll replace the word of with a multiplication sign.

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  Now we'll convert our percent to a decimal—and we're ready to start solving.

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  All we have to do is multiply 0.85 by 20.

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  0.85 times 20 is equal to 17.

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  So 85% of 20 is 17.

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  This means you got 17 correct answers on your test.

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  Let's try another example. We want to find 10% of 90.

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  First, we'll replace the word of with a multiplication sign.

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  Now we'll turn our percent into a decimal.

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  Now all we have to do is multiply 0.10 times 90.

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  0.10 times 90 is equal to 9.

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  Now we can replace the question mark in our problem with a 9.

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  So 10% of 90 equals 9.

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Use decimals to calculate how much these percentages are worth.

You have a coupon for 20% off the price of a book. If the book you want usually costs $10, how much is the coupon worth?

There are 200 families in your town. The newspaper reports that 47% of them have more than two children. How many families in town have more than two children?

Your doctor saw 170 new patients last year. 60% of new patients were women. How many new female patients did your doctor see last year?