PERCENTS
The key to solving most fraction and percent word problems is to identify
the part and the whole. Usually you’ll find the part associated with the
verb is/are and the whole associated with the word of. In the sentence
“Half of the boys are blonds,” the whole is the boys (“of the boys”), and the
part is the blonds (“are blonds”).
28 . Percent Formula
Whether you need to find the part, the whole, or the percent, use the same
formula:
Part = Percent × Whole
Example: What is 12 percent of 25?
Setup: Part = 0.12 × 25.
Example: 15 is 3 percent of what number?
Setup: 15 = 0.03 × Whole.
Example: 45 is what percent of 9?
Setup: 45 = Percent × 9.
29 . Percent Increase and Decrease
To increase a number by a percent, add the percent to 100 percent,
convert to a decimal, and multiply. To increase 40 by 25 percent, add 25
percent to 100 percent, convert 125 percent to 1.25, and multiply by 40.
1.25 × 40 = 50.
