# How do i calculate a percentage?

Divide the number to determine the percentage. Sometimes, percentages can be frustrating because it's not always easy to remember what we learned about them in school. Let Excel do the work for you: Simple formulas can help you find the percentage of a total, for example, or the percentage difference between two numbers. This is essentially what the above calculator does, except that it accepts input in percentage rather than decimal form.

Although the ancient Romans used the Roman numerals I, V, X, L, etc., the calculations were often done in fractions divided by 100. For example, it is very convenient to say that the percent concentration of a specific substance is 15.7% that there are 18.66 grams of substance in 118.66 grams of solution (as in an example in the percent concentration calculator). It should be noted that the second method of calculating the percentage is not used in situations where the denominator is not a factor of 100. Find the change in percentage as an increase or decrease using the Percent Change Calculator.