C Programming Code Examples C > Mathematics Code Examples C Program to find the Sum of First n Natural numbers C Program to find the Sum of First n Natural numbers Program to find the sum of first n natural numbers. We will see two C programs to calculate the sum of natural numbers. In the first C program we are using for loop for find the sum and in the second program we are doing the same using while loop. The user enters the value of n and the program calculate the sum of first n natural numbers using for loop. #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; }