Write a Python Program to Find Sum of Natural Numbers Using Recursion

In Python, we can find the sum of natural numbers using recursion.

Recursion is a technique where a function calls itself repeatedly until a base case is reached.

The base case is the condition when the function stops calling itself and returns a value.

To find the sum of natural numbers using recursion, we need to create a function that calls itself until the base case is reached.

The base case for this problem is when the number becomes zero, and we return zero.

Here is a Python program that finds the sum of natural numbers using recursion:

def sum_of_natural_numbers(n):
    if n == 0:
        return 0
    else:
        return n + sum_of_natural_numbers(n - 1)

In this program, we define a function called sum_of_natural_numbers that takes one argument n, which is the last number in the range of natural numbers we want to sum.

Inside the function, we check if the argument n is equal to zero, which is our base case.

If n is zero, we return zero because the sum of natural numbers from 1 to 0 is zero.

If n is not zero, we return the sum of n and the result of calling the sum_of_natural_numbers function with n-1.

This is where the recursion happens because we call the same function inside itself, but with a smaller argument.

Let’s test our program by finding the sum of natural numbers from 1 to 5:

sum_of_natural_numbers(5)
15

The result is 15, which is the correct sum of natural numbers from 1 to 5.


In conclusion, we can find the sum of natural numbers using recursion in Python by defining a function that calls itself until a base case is reached.

The base case is when the number becomes zero, and we return zero.