This unit will review operations with percents. This is for your information. There will be no formal practice. The only operations you should perform on percents are addition and subtraction. When this is done, you treat them as whole numbers.
Addition and Subtraction of Percents
These operations can be done on percents without any conversion needed.
Example
So, when you add 10% and 20% you get 30%.
10% + 20% = 30% When you subtract 10% from 20% you get 10%.
20% - 10% = 10%
With multiplication and division, percents should be converted to either decimals or fractions before performing these operations. This must be done because of how the decimal point is carried during these operations.
Multiplication and Division of Percents
When performing any multiplication or division with percents, you need to go through the following steps:
- Convert any percents to decimals (or a fraction).
- Perform the operation specified.
- Convert the result back to a percent.
Example of Multiplying Percents
When we multiply 50% by 25% (this would be 25% of 50%), we must:
- Convert any percents to decimals (or a fraction).
50%/100 = .5
25%/100 = .25
- Perform the operation specified.
.5 x .25= .125
- Convert the result back to a percent.
.125 x 100= 12.5% Example of Dividing Percents
When we divide 25% by 75% we must follow the steps outlined above.
- Convert any percents to decimals (or a fraction).
25%/100 = .25
75%/100 = .75
- Perform the operation specified.
- Convert the result back to a percent.
.3333 x 100= 33.33%
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