The factorial of a number is the product of all the integers from 1 to that number. For example, the factorial of 6 (denoted as 6!) is 1*2*3*4*5*6 = 720. Factorial is not defined for negative numbers and the factorial of zero is one, 0! = 1.

### Source Code:

# Python program to find the factorial of a number using recursion def recur_factorial(n): """Function to return the factorial of a number using recursion""" if n == 1: return n else: return n*recur_factorial(n-1) # take input from the user num = int(input("Enter a number: ")) # check is the number is negative if num < 0: print("Sorry, factorial does not exist for negative numbers") elif num == 0: print("The factorial of 0 is 1") else: print("The factorial of",num,"is",recur_factorial(num))

### Output:

Enter a number: -2 Sorry, factorial does not exist for negative numbers

### Output:

Enter a number: 7 The factorial of 7 is 5040

Here, we ask the user for a number and use recursive function recur_factorial() to compute the product up to that number.