# Python math.factorial() – Factorial Function

Contents

## Python math.factorial()

math.factorial(x) function returns the factorial of x as an integer.

## Syntax

The syntax to call factorial() function is

``math.factorial(x)``

where

Note: Since Python v3.9, factorial() does not accept floats with integral values like 5.0.

If x is not integral value, then factorial(x) raises ValueError.

## Examples

### 1. Find factorial of integer

In the following program, we shall read an integer from user, and find its factorial.

Python Program

``````import math

x = int(input('Enter an integer : '))
result = math.factorial(x)
print('Factorial :', result)``````
Copy

Output #1

``````Enter an integer : 5
Factorial : 120``````

Output #2

``````Enter an integer : 0
Factorial : 1``````

Output #3

``````Enter an integer : -4
Traceback (most recent call last):
File "/Users/pe/Desktop/Projects/Python/example.py", line 4, in <module>
result = math.factorial(x)
ValueError: factorial() not defined for negative values``````

### 2. Find factorial of integer online

You can run the following program online and find the factorial of a number.

Python Program

``````import math

x = 7
result = math.factorial(x)
print('Factorial :', result)``````
Run Code Copy

## Summary

In this Python Math tutorial, we learned the syntax of, and examples for math.factorial() function.

## Related Tutorials

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