The word percent means out of 100. Twenty-five percent means 25 out of 100. But what happens when you want to know what percent 4 is out of 5?

In order to calculate percent when 100 is not the denominator, you should view the problem as one of proportions.

or

4  =   x  

   5      100

To solve for x, first multiply 100 x 4, then divide by 5.

Therefore, 4 is 80% of 5.