In this post, we will learn **how to find the sum of natural numbers using recursion in C **Programming language.

**Natural Numbers** are a part of the number system which includes all the positive integers from **1** till **infinity** and are also used for counting. For example: 1, 2, 3, 4, 5, 6, 7, . . . , and so on.

In the program, we will calculate the sum of natural numbers using **recursion**. For example: The Sum of the first **5** Natural Numbers is (1 + 2 + 3+ 4 + 5) = **15**.

So, without further ado, letâ€™s begin this tutorial.

Contents

**C Program to Find the Sum of Natural Numbers using Recursion**

// C Program To Find the Sum of Natural Numbers Using Recursion #include <stdio.h> int Sum(int n); int main(){ int num; // Asking for Input printf("Enter a number: "); scanf("%d", &num); printf("Sum of %d Natural Numbers is %d.", num, Sum(num)); return 0; } int Sum(int n){ if (n != 0) return n + Sum(n - 1); else return n; }

**Output**

```
Enter a number: 7
Sum of 7 Natural Numbers is 28.
```

**How Does This Program Work ?**

** int num;**

In this program, we have declared an int data type variable named as **num**.

** // Asking for Input
printf("Enter a number: ");
scanf("%d", &num);**

Then, the user is asked to enter a number. The value of this number will get stored in **num** named variable.

**int Sum(int n){
if (n != 0)
return n + Sum(n - 1);
else
return n;
}**

Here, we have defined a custom function named **Sum** which will calculate and returns the sum of natural numbers.

Suppose, the user enters the number 5.

Initially, the function **Sum()** is called from **main()** with **5** passed as an argument. Then, the number 5 is added to the result of **Sum(4)**.

In the next call, **4 **is added to the result of **Sum(3)**. This process continues until **n = 0**.

When **n = 0**, our recursive calls terminate and this returns the sum of integers to the main() function.

**Conclusion**

I hope after going through this post, you understand **how to find the sum of natural numbers using recursion in C** Programming language.

If you have any doubt regarding the program, feel free to contact us in the comment section. We will be delighted to help you.

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