# 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.

### PK

PK started DQYDJ in 2009 to research and discuss finance and investing and help answer financial questions. He's expanded DQYDJ to build visualizations, calculators, and interactive tools.

PK lives in New Hampshire with his wife, kids, and dog.

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