Python By Example

Print Factorial of a number

by Jiffin Joachim Gomez on 24th February 2017

This is a simple python script to print factorial of a number.

The factorial of a non-negative integer n, denoted by n! is the product of all positive integers less than or equal to n. For example:

5! = 5 * 4 * 3 * 2 * 1 = 120

The program asks the user to input the number and calculates using the above method. In this program we use a recursive function to calculate the factorial of a number. A recursive function is a self-calling function, which calls itself unless the condition is false. This is the easiest method to calculate factorial of number.

# Python program to find the factorial of a number using recursion

# recursive function
def factorial(n):
   if n == 1:
       return n
       return n * factorial(n-1)

# Getting input from user
num = int(input("Enter the number: "))

# check if the given number is a negative number
if num < 0:
   print("Sorry, factorial does not exist for negative numbers")
elif num == 0:
   print("The factorial of 0 is 1")
   print("The factorial of", num, "is", factorial(num))

Program Output

Enter the number: 5
The factorial of 5 is 120

Enter the number: -5
Sorry, factorial does not exist for negative numbers

Enter the number: 0
The factorial of 0 is 1

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