How to use the Factorial Calculator
The factorial calculator computes n! (n factorial) for any non-negative integer from 0 to 170. The factorial of a number n is the product of all positive integers from 1 up to n. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120. By convention, 0! is defined as 1. This tool uses exact integer arithmetic, so even very large factorials like 100! are shown in full with no rounding.
Factorials appear throughout mathematics and computer science. They are essential in combinatorics: the number of ways to arrange n distinct objects in a row is n!. They also show up in permutations and combinations, probability, and series expansions. Students and professionals use factorials when solving counting problems, working with binomial coefficients, or analyzing algorithms. This calculator gives you the exact value quickly, so you can check homework, explore patterns, or plug results into other formulas.
To use the calculator, type a whole number between 0 and 170 in the input box and click "Get factorial." The maximum of 170 is set because larger factorials have so many digits that they are rarely needed in practice and can be slow to display. If you enter a negative number or a decimal, the calculator will not show a result until you enter a valid non-negative integer. The result is displayed with the full number of digits, and a note shows how many digits the answer contains.
The page is designed to work on phones and tablets as well as desktops. Whether you are learning factorials for the first time or need a quick reference for higher values, this factorial calculator provides accurate, mobile-friendly results with clear SEO content to help you understand and use factorials effectively.