Lesson 10
What Are Percentages?
Let’s learn about percentages.
10.1: Dollars and Cents
Find each answer mentally.
- A sticker costs 25 cents. How many dollars is that?
- A pen costs 1.50 dollars. How many cents is that?
- How many cents are in one dollar?
- How many dollars are in one cent?
10.2: Coins
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Complete the table to show the values of these U.S. coins.
coin penny nickel dime quarter half dollar dollar value (cents) The value of a quarter is 25% of the value of a dollar because there are 25 cents for every 100 cents.
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Write the name of the coin that matches each expression.
- 25% of a dollar
- 5% of a dollar
- 1% of a dollar
- 100% of a dollar
- 10% of a dollar
- 50% of a dollar
- The value of 6 dimes is what percent of the value of a dollar?
- The value of 6 quarters is what percent of the value of a dollar?
Find two different sets of coins that each make 120% of a dollar, where no type of coin is in both sets.
10.3: Coins on a Number Line

A $1 coin is worth 100% of the value of a dollar. Here is a double number line that shows this.

- The coins in Jada’s pocket are worth 75% of a dollar. How much are they worth (in dollars)?
- The coins in Diego’s pocket are worth 150% of a dollar. How much are they worth (in dollars)?
- Elena has 3 quarters and 5 dimes. What percentage of a dollar does she have?
Summary
A percentage is a rate per 100.
We can find percentages of \$10 using a double number line where 10 and 100% are aligned, as shown here:

Looking at the double number line, we can see that \$5.00 is 50% of \$10.00 and that \$12.50 is 125% of \$10.00.
Glossary Entries
- percent
The word percent means “for each 100.” The symbol for percent is %.
For example, a quarter is worth 25 cents, and a dollar is worth 100 cents. We can say that a quarter is worth 25% of a dollar.
- percentage
A percentage is a rate per 100.
For example, a fish tank can hold 36 liters. Right now there is 27 liters of water in the tank. The percentage of the tank that is full is 75%.