Percentages are often used to compare quantities. Like, the price of RAM dropped 20% since last year, and so on.

This is how one would calculate percent change between two numbers:

                        |new value - original value|
 % change = ---------------------------- * 100
                  original value



An Example:

Using a help desk situation, here is how we would find the percent change between 64 calls per day and 28 calls per day:

                        |64 - 28|
 % change = --------- * 100
               64


 % change = 56.25%