Skip to content
Related Articles

Related Articles

Improve Article
Sum of natural numbers using recursion
  • Difficulty Level : Basic
  • Last Updated : 07 Apr, 2021

Given a number n, find sum of first n natural numbers. To calculate the sum, we will use a recursive function recur_sum().
Examples : 
 

Input : 3
Output : 6
Explanation : 1 + 2 + 3 = 6

Input : 5
Output : 15
Explanation : 1 + 2 + 3 + 4 + 5 = 15

 

Below is code to find the sum of natural numbers up to n using recursion : 
 

C++




// C++ program to find the
// sum of natural numbers up
// to n using recursion
#include <iostream>
using namespace std;
 
// Returns sum of first
// n natural numbers
int recurSum(int n)
{
    if (n <= 1)
        return n;
    return n + recurSum(n - 1);
}
 
// Driver code
int main()
{
    int n = 5;
    cout << recurSum(n);
    return 0;
}

Java




// Java program to find the
// sum of natural numbers up
// to n using recursion
import java.util.*;
import java.lang.*;
 
class GFG
{
 
    // Returns sum of first
    // n natural numbers
    public static int recurSum(int n)
    {
        if (n <= 1)
            return n;
        return n + recurSum(n - 1);
    }
     
    // Driver code
    public static void main(String args[])
    {
        int n = 5;
        System.out.println(recurSum(n));
    }
}
 
// This code is contributed by Sachin Bisht

Python




# Python code to find sum
# of natural numbers upto
# n using recursion
 
# Returns sum of first
# n natural numbers
def recurSum(n):
    if n <= 1:
        return n
    return n + recurSum(n - 1)
 
# Driver code
n = 5
print(recurSum(n))

C#




// C# program to find the
// sum of natural numbers
// up to n using recursion
using System;
 
class GFG
{
 
    // Returns sum of first
    // n natural numbers
    public static int recurSum(int n)
    {
        if (n <= 1)
            return n;
        return n + recurSum(n - 1);
    }
     
    // Driver code
    public static void Main()
    {
        int n = 5;
        Console.WriteLine(recurSum(n));
    }
}
 
// This code is contributed by vt_m

PHP




<?php
// PHP program to find the
// sum of natural numbers
// up to n using recursion
 
// Returns sum of first
// n natural numbers
function recurSum($n)
{
    if ($n <= 1)
        return $n;
    return $n + recurSum($n - 1);
}
 
// Driver code
$n = 5;
echo(recurSum($n));
 
// This code is contributed by Ajit.
?>

Javascript




<script>
 
// JavaScript program to find the
// sum of natural numbers
// up to n using recursion
 
// Returns sum of first
// n natural numbers
function recurSum(n)
{
    if (n <= 1)
        return n;
    return n + recurSum(n - 1);
}
 
// Driver code
let n = 5;
document.write(recurSum(n));
 
// This code is contributed by mohan
 
</script>

Output : 



15 

 

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with industry experts, please refer Geeks Classes Live




My Personal Notes arrow_drop_up
Recommended Articles
Page :