Recursively find the factorial of a natural number.

Recursion:

“Recursion is a process in which a problem is defined in terms of itself”.

The problem is solved by repetitively breaking it into a smaller problem which is similar in nature to the original problem.

To compute factorial using recursion the below code helps:

def factorial(n):
 if(n==1 or n==0):
  return 1
 else:
  return n*factorial(n-1)
 
num=int(input())
print(factorial(num))

Here assume num is 6

factorial(6) is called and 6*factorial(5) is returned

6*factorial(5) becomes 6*5*factorial(4)

6*5*factorial(4) becomes 6*5*4*factorial(3)

6*5*4*factorial(3) becomes 6*5*4*3*factorial(2)

6*5*4*3*factorial(2) becomes 6*5*4*3*2*factorial(1)

Finally, for factorial(1) the value 1 is returned

So,

6*5*4*3*2*1=720

The value 720 is printed on the console.