### Overview:

In this article, We will discuss the C Program to Find the Sum of First N Natural Numbers. First of all I would like to explain what a natural number is? Then, I will demonstrate how to calculate the n^{th} term of the natural number. Moreover, I would explain the logic to Find the Sum of First N Natural Numbers. Furthermore, I would write the logic and C Program to Find the Sum of First N Natural Numbers with output.

### Table of contents:

- What is Number?
- What is Natural Number?
- What is the formula to find the Sum of First N Natural Numbers?
- Demonstration to Find the Sum of First N Natural Numbers
- Logic to Find the Sum of First N Natural Numbers
- C Program to Find the Sum of First N Natural Numbers
- Conclusion

### What is Number?

Number is an object that uses digits to perform mathematical tasks. Calculus that is a branch of mathematics included many numbers such as integers, whole numbers, real numbers, and imaginary numbers. Here, I will discuss numbers to perform arithmetic addition operations. Moreover, Number is a combination of digits, some symbols and decimal points. For instance, 127.23 is a rational number. There are many numbers such as whole numbers, natural numbers(positive integers), negative integers, rational numbers etc.

### What is Natural Number?

Natural numbers are the numbers which are positive integers and include numbers from 1 till infinity(∞).

These numbers are countable and are generally used for calculation purposes.

The set of natural numbers is represented by the letter “N”.

N = {1,2,3,4,5,6,7,8,9,10……,∞}

### What is the formula to find the Sum of First N Natural Numbers?

Sums of the First n Natural Numbers

The natural numbers are 1,2,3,4,... so on

The sum of the first n natural numbers, Sn is as follows:

1 + 2 + 3 + 4 + ... + n

Sn = 1 + 2 + 3 + 4 + ... + n

As we know, that

Sn=n[2a+(n−1)d]/2

According to 'n' natural numbers,

The first term = a = 1

The common difference = d = 1

∴ Sn=n[2×1+(n−1)×1]/2

Sn=n[2+n−1]/2

Sn=n[n+1]/2

### Demonstration to Find the Sum of First N Natural Numbers

Let's look at this problem for n=1, 2, 3, 4, and 5 and calculate the sum:

1=1

1+2=3

1+2+3=6

1+2+3+4=10

1+2+3+4+5=15

What is the formula to calculate this sum of n natural number ?

The sum of n Natural numbers is calculated by using following formula:

### Logic to Find the Sum of First N Natural Numbers

**Step 1:**Declare and initialize variable, i,num, s=0.**Step 2:**Enter the value of num i.e. number upto which sum is to be calculated Use Loop to add number.**Step 3:**Any of while, do-while or for loop can be used.**Step 4:**Print the sum

### C Program to Find the Sum of First N Natural Numbers

#include <stdio.h> int main() { int n, count, sum = 0; printf("Enter the value of n(positive integer): "); scanf("%d",&n); for(count=1; count <= n; count++) { sum = sum + count; } printf("Sum of first %d natural numbers is: %d",n, sum); return 0; }

**The output of the Program with code: **

When the above code is executed, it produces the following results:

Enter the value of n(positive integer): 6

Sum of first 6 natural numbers is: 21

**Conclusion:**

This C program to add first N natural numbers includes a single header file: stdio.h to control standard input and output function. As the program is executed, it asks for the value of the number to which the sum of natural numbers is to be found out. Then, the numbers are added using for loop. It can also be done with for and while loop as well. Finally, it displays the sum of numbers stored in integer variable ‘s’.