# How to Find Factorial in Python using factorial() Function

To find factorial in Python you can use `factorial()` function from Standard math Library of Python Programming Language.

The product of an integer and all the integers below it is called factorial. For example, factorial of five ( 5! ) is equal to 120 by multiplying 5 * 4 * 3 * 2 * 1. `!` (Sign of exclamation) is used to represent factorial in mathematics.

`factorial()` function exists in Standard math Library of Python Programming Language. The purpose of this function is to calculate factorial and return its value.

## Python `factorial()` Function Syntax

The syntax of factorial function in python is:
`math.factorial( x )`

## Python `factorial()` Function Parameters

`x` – Any valid Python number (positive). This parameter is required.
Note: if the `x` parameter is not a number or a negative number, factorial function will return an Value Error.

Python 2.x – Yes
Python 3.x – Yes

## Python `factorial()` Function Return Value

The factorial function will return an integer value after calculating the factorial.

## Python `factorial()` Function Example

Output of Python `factorial()` function:
` 120 5040 1307674368000 2432902008176640000 `

Note that if parameter `x` value of `math.factorial( x )` function is negative then Python compiler raises ValueError exception.