Factorial Calculator
Calculate the factorial of a non-negative integer quickly. Factorials are common in permutations, combinations, and probability. It is useful for study, lab preparation, engineering notes, or checking a calculation where consistent units matter.
How to use this calculator
Enter whole-number values within the range supported by the calculator. Check whether the problem is about order (permutations) or selection without order (combinations) before choosing the calculation.
Formula
n! = n Γ (nβ1) Γ ... Γ 1, with 0! = 1.
Quick check
Use the calculator as a quick verification tool as well as a way to get the final number. Understanding what the result represents is just as important as the number itself. For technical or academic work, write down the units alongside the numbers. A mathematically correct calculation can still be misleading if the units are wrong.