Factorial Calculator

Calculate the exact factorial of any whole number up to 5,000, with the digit count.

What is the Factorial Calculator?

n! (n factorial) is the product of all positive integers from 1 to n. By definition 0! = 1.

How does it work?

The product is computed with arbitrary-precision integers, so every digit is exact.

Formula

n! = n × (n − 1) × … × 2 × 1

Example

5! = 120. 20! = 2,432,902,008,176,640,000 (about 2.43 × 10¹⁸).

Frequently asked questions

Why is 0! equal to 1?

There is exactly one way to arrange zero items, and it keeps formulas like nCr consistent.

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