C Program to Find the sum of First N natural Number
In this article, we will see C Program to Find the Sum of First N Natural Numbers. A Natural number is the same as a Counting number. They are used to Count the number of real physical objects. Natural numbers start from 1 and go on infinite.
The positive numbers 1,2,3 ... are known as natural numbers.
The formula for Sum of First n natural numbers is n(n+1)/2.
If you want to add the first 5 Natural numbers then we find the Sum of 1+2+3+4+5 =15.
Flow Diagram:
Code:

Start.

Declare and initialize variable, i,num, s=0.

Enter the value of num i.e. number up to which sum is to be calculated.

Use Loop to add numbers. Any of while, dowhile or for loop can be used.

Print the sum.

Stop.
Algorithm:
Code:
#include <stdio.h>
int main()
{
int n;
scanf("%d",&n); int sum = 0;
for(int i=1;i<=n;i++)
// is same as writing sum = sum + i
sum += i;
printf("Sum is %d",sum);
return 0;
}
Output:
5
Sum is 15