In this Post, you will learn **how to calculate the sum of natural numbers using the C** Programming language.

The Positive numbers 1, 2, 3, . . . which are used for counting and ordering are known as **natural numbers**.

Today, we will write two C Programs to calculate the Sum. First Using For loop statement and Second one using while Loop Statement.

So, without further ado, let’s begin the tutorial.

**C Program to Calculate the Sum of Natural Numbers** **Using for Loop**

// C Program To Calculate the Sum of Natural Numbers #include <stdio.h> int main(){ int i, n, sum = 0; // Asking for Input printf("Enter a Positive Integer: "); scanf("%d", &n); // logic for (i = 1; i <= n; ++i){ sum = i + sum; } printf("The Sum of %d Natural Numbers is: %d.", n, sum); return 0; }

**Output**

```
Enter a Positive Integer: 18
The Sum of 18 Natural Numbers is: 171.
```

**How Does This Program Work ?**

` `** int i, n, sum = 0;**

In this example, we have declared three integer type variables named as **i**, **n** and **sum** respectively.

** // Asking for Input
printf("Enter a Positive Integer: ");
scanf("%d", &n);**

Then, the user is asked to enter a Positive Integer. This value will be stored in the **n** named variable.

** // logic
for (i = 1; i <= n; ++i){
sum = i + sum;
}
**

**for loop** statement is used to calculate the sum of natural numbers up to **n**. The value is stored in the **sum** variable.

** printf("The Sum of %d Natural Numbers is: %d.", n, sum);**

Finally, the value of the sum is printed using **printf()** function.

Some of the used terms are as follow:

**#include <stdio.h>** – In the first line we have used #include, it is a preprocessor command that tells the compiler to include the contents of the stdio.h(standard input and output) file in the program.

The **stdio.h **is a file which contains input and output functions like** scanf()** and** printf()** to take input and display output respectively.

**Int main()** – Here main() is the function name and int is the return type of this function. The Execution of any Programming written in C language begins with main() function.

**scanf()** – scanf() function is used to take input from the user.

**printf()** – printf() function is used to display and print the string under the quotation to the screen.

**For loop **– A loop is used for initializing a block of statements repeatedly until a given condition returns false.

**// **– Used for Commenting in C.

**Find the Sum of Natural Numbers Using while Loop**

// C Program To Calculate the Sum of Natural Numbers #include <stdio.h> int main(){ int i, n, sum = 0; // Asking for Input printf("Enter a Positive Integer: "); scanf("%d", &n); // logic i = 1; while (i <= n){ sum = sum + i; i++; } printf("The Sum of %d Natural Numbers is: %d", n, sum); return 0; }

**Output**

```
Enter a Positive Integer: 10
The Sum of 10 Natural Numbers is: 55
```

**while Loop** – In the while loop, the statements inside the body of the while loop keeps executing until it is evaluated to False.

**Conclusion**

I hope after going through this post, you understand how to calculate the sum of Natural Numbers using C Programming language.

If you have any doubts regarding the topic, feel free to contact us in the Comment Section. We will be delighted to help you.