Percents and Decimals
Objective Learn how percents and decimals are
related, and how to convert from one to the other.
In this lesson, you will learn a technique for relating
decimals to percents. You should realize that the calculations
involved in converting decimals to percents are easier, since
percents represent ratios that compare a number to 100, and
decimals represent fractions with denominators that are powers of
10.
Expressing a Decimal as a Percent
The following example shows how a proportion can be used to
change a decimal to a percent.
Example 1
Convert 0.365 to a percent.
Solution
We need to change the decimal 0.365 to a percent. First
express 0.365 as a fraction.
To find the percent, set up and solve a proportion.
 |
 |
|
| 100 · 365 |
= 1,000 · x |
Cross multiply. |
| 36,500 |
= 1,000 x |
Divide each side by 1,000. |
| 36.5 |
= x |
|
Expressing a Percent as a Decimal
Let's see how to reverse the procedure. In other words, how
does one express a percent as a decimal? This change can be
accomplished by simply writing the percent as a fraction with 100
as the denominator, and then changing that fraction to a decimal.
Here are some good examples.
Example 2
Express 23% as a decimal.
Solution
Write 23% as a fraction with a denominator of 100.
Dividing by 100 results in the movement of the decimal point
in the divisor two places to the left. So,  . Therefore, 23% = 0.23.
Example 3
Example 4
Computing with percents is an extremely important skill. Be
sure to solve numerous problems by yourself. This will help you
solidify your understanding of the concept of percent, as well as
help with your computational skills involving decimals. |
