Python | math.factorial() function

In Python, math module contains a number of mathematical operations, which can be performed with ease using the module. math.factorial() function returns the factorial of desired number.

Syntax: math.factorial(x)

Parameter:
x: This is a numeric expression.
Returns:  factorial of desired number.
Time Complexity: O(n) where n is the input number.
Auxiliary space: O(1)

Code #1: 

Python3

# Python code to demonstrate the working of factorial()

# importing "math" for mathematical operations
import math

x = 5

# returning the factorial
print ("The factorial of 5 is : ", end ="")
print (math.factorial(x))

Output:

The factorial of 5 is : 120

Code #2: 

Python3

# Python code to demonstrate the working of factorial()

# importing "math" for mathematical operations
import math

x = 5
y = 15
z = 8

# returning the factorial
print ("The factorial of 5 is : ", math.factorial(x))
print ("The factorial of 15 is : ", math.factorial(y))
print ("The factorial of 8 is : ", math.factorial(z))

Output:

The factorial of 5 is :  120
The factorial of 15 is :  1307674368000
The factorial of 8 is :  40320

Code #3: Throws ValueError if x is not integer 

Python3

# Python code to demonstrate the working of factorial()

# importing "math" for mathematical operations
import math

# when x is not integer
print ("math.factorial(13.7) : ", math.factorial(13.7))

Output:

ValueError: factorial() only accepts integral values