Input two values. The first value will be the percentage of the second one and the result will show up automatically. You will also find a copy of the formula, as you might need it to use it yourself. It's easy to calculate it, just divide the percentage by 100 (which obviously just shifts it by two decimal points, i.e. 25/100 is 0.25) and then multiply it with the value that you want to find the percentage of.