A percentage is a way to express a number as a part of a whole. For example 50 becomes 05 20 becomes 02 1 becomes 001 and so on. Method 2 Step 1.
Calculate the difference subtract one value form the other ignore any negative sign.
So 40 would be 40 divided by 100 or40. To calculate a percentage we look at the whole as equal to 100. If you eat 2 apples then you have eaten 210 100 20 of your apples and you are left with 80 of your original apples. Convert that to a percentage by multiplying by 100 and adding a.