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 Introduction 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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Writing percentages

As you saw in the slideshow, every percentage has two parts: a number and the percent sign ( % ). When you write a percentage, you'll write the number first, then the percent sign. Let's try it! How would you write this percentage?

nine percent

First, we'll write the number, nine , and then the percent sign ( % ). So our percentage will look like this:

9%

Try This!

Try writing the correct percentage in the box.

Reading percentages

When you read a percentage out loud, you'll need to read two parts: the number and the percent sign ( % ). Let's look at an example:

25%

25% is twenty five out of one hundred . We'd read 25% like this:

twenty-five percent

Sometimes percentages might have a decimal . For example:

7.5%

Here, 7.5% means we have seven-and-a-half out of one hundred . We'd read it like this:

seven point five percent

OR

seven and a half percent

You can read any percentage with a decimal point like this. How about 10.25% ? That's ten and one quarter out of one hundred , so we'd read it as ten point two five percent , or ten and a quarter percent .

Try This!

Try reading each of the percentages below aloud.

Comparing percentages

Let's imagine you're shopping for apple juice. You find two different kinds—one contains 20% real juice, while the other contains 50% real juice.

Do you know which bottle has more real juice? Since both bottles are the same size, we can simply compare the numbers to see which percentage is larger .

50 is larger than 20 , so 50% is a larger percentage than 20% . The larger the number next to the percent sign, the larger the percentage.

What about these percentages?

7% and 17%

Which is larger? Again, we'll look to see which number is larger. 17 is larger than 7 , so 17% is a larger percentage than 7% .

Comparing percentages with decimals

What if you had to compare two percentages like this?

5.4% and 5.5%

At first glance, it might be difficult to tell which percentage is larger. Remember, this is just another way of asking, "Which is larger, five and four-tenths of a percent or five and five-tenths of a percent ?" Since the first number is the same for both fractions, we'll compare the numbers to the right of the decimal place.

5 is larger than 4 , so 5.5% is larger than 5.4% .

What about these percentages?

5.55% and 5.56%

Again, since the first number is the same, we'll compare the numbers to the right of the decimal place.

56 is larger than 55 , so 5.56% is larger than 5.55% .