Michael asked the following: "When finding a percentage difference of two figures, e.g. 400 and 500,
"400500 = 100, so 100/400x100 = 25%" "But if you do 100/500x100 = 20%??" Thank you for this, Michael! The answer is that it depends on what you want to know: If you want to know how much more a larger number (500) is as a percentage of a smaller number (400) then use the first method  you correctly found that the difference (100) is a quarter (25%) of 400 (the smaller number). If you want to know how much smaller a number (400) is than a larger one (500), the use the second technique  you correctly showed that the difference (100) is 1/5 (20%) of 500.
