Converting Percents to Decimals and
Converting Decimals and Fractions to Percents
Percents are used to denote portions as ratios over 100. For example, if a company's labor force is 25% part-time workers, then 25 out of every 100 workers is part-time. Of course, the company may not even have 100 employees, but the percentage gives you an idea of how much one portion contributes to the whole.
When you add up all of the percentages of the various parts, the total must be 100%. For example, the company's work force may 25% part-time workers, 65% full-time workers, and 10% independent contractors. Notice that 25% + 65% + 10% = 100%.
Percents can be expressed as decimals simply by moving the decimal point two units to the left, or by dividing by 100. For example, 25% is equivalent to 0.25. And you can convert decimals to percents simply by moving the decimal point two units to the right, or by multiplying by 100.
In business, science, and data analysis, people often need to convert fractions to percents. You can do this in two easy steps. First, divide the numerator by the denominator to obtain a decimal. Then move the decimal point two units to the right to obtain the percent.
Example: Jen owns a small business and one fifth of her employees are male. To express this proportion as a percent, first write one fifth = 1/5. Then 1 divided by 5 = 0.2, and 0.2 = 20%. So one fifth and 20% are completely equivalent.
Another example: If 3/8 of a town's residents are registered to vote, what percent is not registered? First, convert 3/8 into 0.375. Next, 0.375 = 37.5%. Since all the percents must add up to 100%, we can find the other percent by subtraction. 100% - 37.5% = 62.5%, so 62.5% of the town's residents are not registered to vote.
You can also convert a percent to a fraction by placing the percent in the numerator position and placing 100 in the denominator position. For instance, 25% = 25/100. In many cases, the resulting fraction can be reduced. For example, 25/100 = 1/4.
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