Which equation correctly relates part P, whole W, and percent?

Which equation correctly relates part P, whole W, and percent?

• A. P = W × %
• B. P = W ÷ %
• C. P = W × 100
• D. P = W + %

Answer: (A)

Percent tells us what fraction of the whole we have. The part is that fraction of the whole, so you multiply the whole by the percent written as a decimal. That’s why the relation P = W × % works: the percent is used in decimal form (for example, 25% becomes 0.25). For instance, if the whole is 200 and the percent is 25%, then P = 200 × 0.25 = 50. Dividing by a percent would not give a part of the whole, multiplying by 100 scales the whole by 100, not by the desired fraction, and adding the percent to the whole doesn’t form a part of the whole.

Percent tells us what fraction of the whole we have. The part is that fraction of the whole, so you multiply the whole by the percent written as a decimal. That’s why the relation P = W × % works: the percent is used in decimal form (for example, 25% becomes 0.25).

For instance, if the whole is 200 and the percent is 25%, then P = 200 × 0.25 = 50.

Dividing by a percent would not give a part of the whole, multiplying by 100 scales the whole by 100, not by the desired fraction, and adding the percent to the whole doesn’t form a part of the whole.