Percents (%)

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

One percent (1%) means 1 per 100.

1 in 100
1% of this line is shaded green: it is very small isn't it?

 

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

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

Try it Yourself:

numbers/images/ani-pct.js

Examples:

grid 100 of 100 equals 100%  

100% means all

Example:

100% of 80 is 100100 × 80 = 80

grid 50 of 100 equals 50%  

50% means half

Example:

50% of 80 is 50100 × 80 = 40

grid 5 of 100 equals 5%  

5% means 5100ths

Example:

5% of 80 is 5100 × 80 = 4

Using Percent

numbers/images/percentage.js

Use the slider and try some different numbers
(What is 40% of 80? What is 10% of 200? What is 90% of 10?)

Because "Percent" means "per 100" think:

"this should be divided by 100"

So 75% really means 75100

And 100% is 100100, or exactly 1
(100% of any number is just the number, unchanged)

And 200% is 200100, or exactly 2
(200% of any number is twice the number)

 

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


pie 1/2  
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% = 25100

And  25100 × 80 = 20

So 25% of 80 is 20

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

15% = 15100

And  15100 × 200   =  15 × 200100 
    =  15 × 2  
    30 apples

30 apples are bad

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

As a fraction, 10200 = 0.05

As a percentage it is: 10200 x 100 = 5%

 

5% of those apples are bad

skateboard

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

 

First, find 25% of $120:

25% = 25100

And  25100 × $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

Calculation Trick

This little rule can make some calculations easier:

x% of y = y% of x

Example: 8% of 50

8% of 50 is the same as 50% of 8

And 50% of 8 is 4

So 8% of 50 is also 4

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.

 

877,878,879, 1301, 1302,880, 1303, 1304, 3501, 3502