factorial.py

__author__ = 'Avinash'

num = int(input("Enter a number: "))
factorial = 1
if num < 0:
    print("Please enter a positive integer")
elif num == 0:
    print("The factorial of 0 is 1")
else:
    for i in range(1, num + 1):
        factorial *= i
    print("The factorial of", num, "is", factorial)