Percents

What are percentages?

A percentage is another way of writing a decimal. Just like decimals, a percentage is a part of a whole. Basically, it's less than 1 whole thing, but more than 0.

We use percentages all the time in real life. For example, have you ever left a fifteen percent tip at a restaurant? Or bought something on sale for twenty percent off? Those are both percentages—15 percent and 20 percent.

Click through the slideshow to learn how percentages work.

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  Let's look at some more percentages from real life. In Intro to Decimals, you learned that 25 cents is 0.25 of a dollar.

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  Another way to say this is that 0.25 cents is 25 percent of a dollar.

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  What about two quarters, or fifty cents? That's 0.50, or 50 percent of a dollar.

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  Three quarters would be 75 cents, or 75 percent of a dollar.

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  And four quarters, or 100 cents, would be 100 percent of a dollar... 

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  And four quarters, 100 cents, would be 100 percent of a dollar...or one whole dollar.

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  Percent literally means "per hundred", or "out of a hundred".

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  In our example, every dollar is made up of one hundred pennies, or 100 cents.

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  So you could say that each penny is equal to 1 percent of a dollar.

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  Let's look at another example. Let's imageine we cut a pizza into five slices.

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  Each slice is equal to one-fifth, or .20, of the pizza.

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  We know that one slice is equal to .20 because .20 + .20 + .20 + .20 + .20 = 1.00.

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  So we can also say that one slice is equal to 20 percent of the pizza.

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  We can use the percent sign (%) to write that as 20%.

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  Right now, we have one whole pizza, or 100% of the pizza.

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  What if we take away one slice? Now we have 80%. That's because we removed a slice, or 20% of the pizza.

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  What if we take away two slices? Now we have 60%.

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  Now we have 40% left.

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  Even though we have less than one pizza, we still have more than zero pizzas. We have a percentage of the pizza left.

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