Percentages

Percentages:

To write a % to a decimal, drop the % and move the decimal two places to the left.
For example, 75% =
.75   You must change a % to a decimal in order to calculate with a percentage.

To write a decimal as a percent, move the decimal two places to the right and place a % sign to the right of the number. For example, .25 = 25%

To write a % as a fraction, drop the % and place the number over 100 and reduce, if possible.
For example 12.5% would be

      

To write a fraction as a percent, multiply the fraction by 100% and then simplify the resulting fraction.  For example,

                (Note: you may have to round)

Example 1:  A refrigerator sells for $650. If the sales rate is 8.5%, what is the total price?0

Tax = 650(0.085) = $55.25

Total Price = 650 + 55.25 = $705.25

Example 2:  John makes $2500 a month in income. If he spends $300 for entertainment, what percent of his monthly income is spent on entertainment?

      

Example 3:  A used car is sold for 60% of itís original value of $22,000.  What is the selling price of the used car?

New Price = 22,000 (0.60) = $13,20

Changing Percent to a Decimal and then to a Fraction:

Percent means "out of a hundred."  First, convert the percent to a decimal by removing the % sign and moving the decimal two places to the left. Place the resulting number over 100 and then remove the decimal sign.  For example:

           

The fraction may now be reduced:

               

To convert a fraction to a percent, remember that a fraction means division so divide. The quotient now may be transformed to a percent by moving the decimal two places to the right and inserting a % sign. For example:

    3/4 = 0.75 = 75%

    3/2 = 1.5 = 150%

    5/8 = 0.625 = 62.5%

General Algebra Tips

The views and opinions expressed in this page are strictly those of Mary Lou Baker.
The contents of this page have not been reviewed or approved by Columbia State Community College.

This page was edited on 28-Jan-2013