Percentages and Decimals

Percentages and decimals are related to each other and can be converted from one form to the other. Let's see how to do that.

Converting a percentage to decimal

Example:

Following is a cookie box containing 100 assorted cookies of 2 different shapes.
40% of the whole box of cookies is round-shaped cookies. Convert this percentage to a decimal.



If the whole box of cookies has a value of 100% then 40% of that is round cookies.

40%  =   40
100
   =  40 ÷ 100
   =  0.4
If the whole box of cookies has a decimal value of 1.0, then 0.4 of it is round cookies.

ANSWER CHECK

Using percent value

Round cookies  =  40% of 100 cookies
   =   40
1001
 × 1001 cookies
   =   40cookies

Using decimal value

Round cookies  =  0.4 of 100 cookies
   =  0.4 × 100 cookies
   =  40 cookies

Answers match!


Converting a decimal to percentage

Example:

Following is a cookie box containing 100 assorted cookies of 2 different shapes.
0.6 of the whole box of cookies is square-shaped cookies. Convert this decimal number to a percentage.



If the whole box of cookies has a value of 1.0 then 0.6 of that is square-shaped cookies.

0.6  =  6 ÷ 10
   =   6
10
   =   60
100
   =  60%
If the whole box of cookies has a percent value of 100%, then 60% of it is square-shaped cookies.

ANSWER CHECK

Using decimal value

Round cookies  =  0.6 of 100 cookies
   =  0.6 × 100 cookies
   =  60 cookies

Using percent value

Square cookies  =  60% of 100 cookies
   =   60
1001
 × 1001 cookies
   =   60cookies

Answers match!


Quick tricks:
  1. To convert a percentage to decimal, simply divide the number by 100%.
  2. To convert a decimal to percentage, simply mulltiply the number by 100%.