Decimals, Fractions and Percentages
Decimals, Fractions and Percentages are just different ways of showing the same value:
A Half can be written...
... as a fraction:
\frac{1}{2}
... as a decimal:
0.5
... as a percentage:
50%

A Quarter can be written...
... as a fraction:
\frac{1}{4}
... as a decimal:
0.25
... as a percentage:
25%

Here, have a play with it yourself:
Example Values
Here is a table of commonly used values shown in Percent, Decimal and Fraction form:
Percent  Decimal  Fraction 

1%  0.01  ^{1}/_{100} 
5%  0.05  ^{1}/_{20} 
10%  0.1  ^{1}/_{10} 
12½%  0.125  ^{1}/_{8} 
20%  0.2  ^{1}/_{5} 
25%  0.25  ^{1}/_{4} 
33^{1}/_{3}%  0.333...  ^{1}/_{3} 
50%  0.5  ^{1}/_{2} 
75%  0.75  ^{3}/_{4} 
80%  0.8  ^{4}/_{5} 
90%  0.9  ^{9}/_{10} 
99%  0.99  ^{99}/_{100} 
100%  1  
125%  1.25  ^{5}/_{4} 
150%  1.5  ^{3}/_{2} 
200%  2 
Conversions!
From Percent to Decimal
To convert from percent to decimal divide by 100 and remove the % sign.
An easy way to divide by 100 is to move the decimal point 2 places to the left:
From Percent  To Decimal  
move the decimal point 2 places to the left 
Don't forget to remove the % sign!
From Decimal to Percent
To convert from decimal to percent multiply by 100%
An easy way to multiply by 100 is to move the decimal point 2 places to the right:
From Decimal  To Percent  
move the decimal point 2 places to the right 
Don't forget to add the % sign!
From Fraction to Decimal
To convert a fraction to a decimal divide the top number by the bottom number:
Example: Convert \frac{2}{5} to a decimal
Divide 2 by 5: 2 ÷ 5 = 0.4
Answer: \frac{2}{5} = 0.4
From Decimal to Fraction
To convert a decimal to a fraction needs a little more work.
Example: To convert 0.75 to a fraction
Steps  Example 

First, write down the decimal "over" the number 1: 
\frac{0.75}{1} 
Multiply top and bottom by 10 for every number after the decimal point (10 for 1 number,100 for 2 numbers, etc): 
\frac{0.75 × 100}{1 × 100} 
This makes a correctly formed fraction: 
\frac{75}{100} 
Then Simplify the fraction: 
\frac{3}{4} 
From Fraction to Percentage
To convert a fraction to a percentage divide the top number by the bottom number, then multiply the result by 100%
Example: Convert \frac{3}{8} to a percentage
First divide 3 by 8: 3 ÷ 8 = 0.375
Then multiply by 100%: 0.375 × 100% = 37.5%
Answer: \frac{3}{8} = 37.5%
From Percentage to Fraction
To convert a percentage to a fraction, first convert to a decimal (divide by 100), then use the steps for converting decimal to fractions (like above).
Example: To convert 80% to a fraction
Steps  Example 

Convert 80% to a decimal (=80/100): 
0.8 
Write down the decimal "over" the number 1: 
\frac{0.8}{1} 
Multiply top and bottom by 10 for every number after the decimal point (10 for 1 number,100 for 2 numbers, etc): 
\frac{0.8 × 10}{1 × 10} 
This makes a correctly formed fraction: 
\frac{8}{10} 
Then Simplify the fraction: 
\frac{4}{5} 