# Factorial Calculator

Written by:
PK

Below is a factorial calculator, which will calculate the factorial of a number n. Enter a positive integer to return the factorial.

## What is a Factorial?

A factorial is the product of a number and all positive integers that are less than that number.

It's a useful construct, found often when computing combinations and permutations of a set.

## Formula for Factorials

The formula for a factorial is:

n! = 1 * 2 * 3 * ... * (n-2) * (n-1) * n

### Example Factorial Calculation

For example, let's say you want to take the factorial of 7. Here's how it works:

7! = 1*2*3*4*5*6*7 = 5040

## Using the Factorial Calculator

In the text box at the top, enter the Number n you'd like to compute the factorial for, then click the Compute Factorial button. We'll do the math and put the result in the Factorial box.