HOW TO UNDERSTAND PERCENTS

 

Percents are used everywhere, so you need to be able to use them.

'Cent' is Latin for one in a hundred, 1/100, that is, one one-hundredth of something. Fifteen percent means 'fifteen per hundred', and is the same as the fraction 15/100 and the decimal 0.15

 

These are the three ways to write the same thing:

15% = 15/100 = 0.15

See the chart at the bottom of this page.

 

0.85 = 85%

We can find any percent of a given number by changing the percent to a decimal and multiplying. 

 

99% of 50 = 50 X .99

 

One hundred percent of a number is just the number itself. Two hundred percent of a number is twice that number.

200% of 50 = 50 X 2.0 = 100

 

Example: Find 35% of 300:

First change 35% to a decimal by moving the decimal point 2 places to the left.

35% = 0.35

Then multiply:

0.35 x 300 = 

105

 

Understand, and then memorize, the connections in this chart:

fraction percent decimal
5/100 5% .05
1/10 10% 0.10
12.5/100 12.5% .125
1/5 20% 0.20
1/4 25% 0.25
1/3 33% 0.33
1/2 50% 0.50
2/3 67% 0.67
3/4 75% 0.75
9/10 90% 0.90

 

 

To get decimals from fractions, divide the top by the bottom.

For example, 3/4 = 3 divided by four. That equals 0 .75