## Percentages

A percentage is a way of writing a fraction with a denominator of 100.

Percentage means "out of 100" or "per hundred"

Calculations involving percentages often require multiplication or division by 100.

x percent, written x%, means x100 (or x parts out of 100)

 Examples Answers Write 40% as a fraction 40% = 40⁄100        = 20⁄50 = 10⁄25 = 2⁄5 Write the fraction 7⁄10 as a percentage 70%

Percentage Calculations

Below are some of the types of problem that use percentages.

Percentage of a quantity:

To find x percent of a quantity. Calculate: x100 × (the quantity)

 Example Answer Find 8% of 300 300 × 8⁄100 = 24

One quantity as a percentage of another quantity:

To find a out of b as a percentage. Calculate: ab × 1001

 Example Answer Write 13 out of 20 as a percentage. 13⁄20 × 100⁄1 = 65%

Increasing a quantity by a percentage:

To increase a quantity by x percent. Calculate: Example Answer Increase 50 by 8% Decreasing a quantity by a percentage:

To decrease a quantity by x percent. Calculate: Example Answers Decrease 50 by 8% 