Introductions To Percentages

Percentages (%)

When you say "Percent" you are really saying "per 100"

	So 50% means 50 per 100 (50% of this box is green)		And 25% means 25 per 100 (25% of this box is green)

Examples:

		100% means all. Example: 100% of 80 is 100/100 × 80 = 80
		50% means half. Example: 50% of 80 is 50/100 × 80 = 40
		5% means 5/100ths. Example: 5% of 80 is 5/100 × 80 = 4

Using Percent Because "Percent" means "per 100" you should think "this should always be divided by 100" So 75% really means 75/100 And 100% is 100/100, or exactly 1 (100% of any number is just the number, unchanged) And 200% is 200/100, or exactly 2 (200% of any number is twice the number) Use the slider on the left and try some different numbers (example, what is 40% of 80?)

A Percent can also be expressed as a Decimal or a Fraction

A Half can be written... As a percentage: 50% As a decimal: 0.5 As a fraction: 1/2

Read more about this at Decimals, Fractions and Percentages.

Some Worked Examples

Example: Calculate 25% of 80

25% = ²⁵/₁₀₀

(²⁵/₁₀₀) × 80 = 20

So 25% of 80 is 20

Example: 15% of 200 apples were bad. How many apples were bad?

15% = ¹⁵/₁₀₀

(¹⁵/₁₀₀) × 200 = 15 × 2 = 30 apples

30 apples were bad

Example: if only 10 of the 200 apples were bad, what percent is that?

As a fraction, 10/200 = 0.05
As a percentage it is: (10/200) x 100 = 5%
5% of those apples were bad

Example: A Skateboard is reduced 25% in price in a sale. The old price was $120. Find the new price

First, find 25% of $120:
25% = ²⁵/₁₀₀

(²⁵/₁₀₀) × $120 = $30

25% of $120 is $30

So the reduction is $30

Take the reduction from the original price

$120 - $30 = $90

The Price of the Skateboard in the sale is $90