# Sum of natural numbers using recursion

• Difficulty Level : Easy
• 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 :

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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 using namespace std; // Returns sum of first// n natural numbersint recurSum(int n){    if (n <= 1)        return n;    return n + recurSum(n - 1);} // Driver codeint main(){    int n = 5;    cout << recurSum(n);    return 0;}

## Java

 // Java program to find the// sum of natural numbers up// to n using recursionimport 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 numbersdef recurSum(n):    if n <= 1:        return n    return n + recurSum(n - 1) # Driver coden = 5print(recurSum(n))

## C#

 // C# program to find the// sum of natural numbers// up to n using recursionusing 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



## Javascript



Output :

15

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