Percentages (%)

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

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

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

Examples:

100%  

100% means all.

Example:

100% of 80 is  100  × 80 = 80
100
50%  

50% means half.

Example:

50% of 80 is  50  × 80 = 40
100
5%  

5% means 5/100ths.

Example:

5% of 80 is  5  × 80 = 4
100

Using Percent

Because "Percent" means "per 100" think:

"this should 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 side and try some different numbers
(What is 40% of 80? What is 10% of 200? What is 90% of 10?)

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
And   25  × 80 = 20
100

 

So 25% of 80 is 20

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

15% =   15
100
And   15  × 200  =  15 ×  200   =  15 × 2  =  30 apples
100 100

 

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
And   25  × $120 = $30
100

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

The Word

"Percent" comes from the latin Per Centum. The latin word Centum means 100, for example a Century is 100 years.

Percent vs Percentage

My Dictionary says "Percentage" is the "result obtained by multiplying a quantity by a percent". So 10 percent of 50 apples is 5 apples: the 5 apples is the percentage.

But in practice people use both words the same way.