Factorial Calculator
Compute the factorial n! of a whole number, exactly — even very large values.
n! (factorial)
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Number of digits
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Approximate value
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Results update as you type.
About this calculator
The factorial of n (written n!) is the product of every whole number from 1 up to n. 5! = 5 × 4 × 3 × 2 × 1 = 120. Factorials count the ways to arrange n items and appear throughout combinatorics. This calculator returns the exact value with arbitrary precision and the digit count.
Frequently asked questions
What is a factorial used for?
A factorial counts arrangements: n! is the number of distinct orderings of n items. It is the building block of permutations and combinations.
What is 0! (zero factorial)?
By definition 0! = 1. There is exactly one way to arrange an empty set, so the empty product is 1.
Results are estimates for general guidance only, not financial, medical or tax advice.