❗ Factorial Calculator

About this Factorial Calculator

This factorial calculator multiplies a whole number by every whole number below it: 5! = 5 × 4 × 3 × 2 × 1 = 120. Factorials grow extremely fast and are the building blocks of permutations and combinations — counting how many ways things can be arranged or chosen.

How to use it

1. Enter a whole number between 0 and 170.
2. Click Calculate n!.
3. Read the factorial value and how many digits it has.

Example

10! = 3,628,800 — the number of different orders in which 10 people can stand in a line.

Frequently asked questions

Why is 0! equal to 1?

By definition. It keeps the formulas for combinations working: there is exactly one way to arrange nothing.

Why does it stop at 170?

171! is bigger than the largest number a normal calculator (and this browser) can store, about 1.8 × 10³⁰⁸.

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