ParaPro Math Study Guide: Percentages

This page of our online ParaPro Study Guide covers percentages. You will learn how to convert a fraction to a percentage, find a percentage of a value, and change a value be a percentage. Four examples are included to help you master these skills. Once you are comfortable with this material you can try the percentages review test at the bottom of the page.

What are Percentages?

Percentages are a way of expressing a portion of a whole in terms of a fraction of 100. The term “percent” means “per hundred,” so when you express a value as a percentage, you’re essentially describing how many parts out of 100 something represents.

For example, if you have 30 out of 100 marbles, you can express this as 30%. This means you have 30 parts out of every 100 parts.

Percentages are commonly used to compare relative values, express proportions, or describe changes over time. They’re extensively used in finance, statistics, everyday calculations, and many other fields.

Working with Percentages

To convert a fraction to a percentage, you divide the numerator by the denominator to get the equivalent decimal value. Multiply the decimal value by $100$ to get the percentage (represented by the symbol $\%$).

To find a certain percentage of a value, you multiply the percentage’s decimal equivalent by the number.

To increase or decrease a value by a percentage, you add or subtract the percentage to/from $100 \%$.

Example 1

What is the decimal $.2$ represented as a percentage?

Multiply $.2$ by $100$ to get the percentage.

$.2 \cdot 100 = 20 \%$

Example 2

What is the fraction $6/8$ represented as a percentage?

To convert $6/8$ to a decimal, divide the numerator by the denominator.

$6 ÷ 8 = .75$

Example 3

What is $30 \%$ of $80$?

To find $30 \%$ of $80$, you multiply the percentage’s decimal equivalent by the number.

$\dfrac{30}{100} = .3$

$.3 \cdot 80 = 24$

Example 4

What do you get if you increase $25$ by $20 \%$?

To increase the value of $25$ by $20 \%$, you add $20 \%$ to $100 \%$.

To find $120 \%$ of $25$, you multiply the percentage’s decimal equivalent by the number.

$\dfrac{120}{100} = 1.2$

$1.2 \cdot 25 = 30$

Now that you have learned about percentages and reviewed these four examples, you should know what to expect for the ParaPro test. Before moving on, try the percentages review test to ensure that you are fully prepared.


Percentages Review Test


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