In this tutorial, i am going to show you how to find sum of first n natural in c program with the help of for loop, while loop, function, and recursion.

Using the following mathematical formula to find the sum of n natural numbers in c program; as follows:

Sum of n natural number = n * (n + 1) / 2

## All C Programs find the Sum of First n Natural numbers

- C Program to find the Sum of First n Natural numbers using For Loop
- C Program to find the Sum of First n Natural numbers using While Loop
- C Program to find the Sum of First n Natural numbers using Function
- C Program to find the Sum of First n Natural numbers using Recursion

### C Program to find the Sum of First n Natural numbers using For Loop

#include<stdio.h> int main() { int Number, i, Sum = 0; printf("\nPlease Enter any Integer Value\n"); scanf("%d", &Number); for(i = 1; i <= Number; i++) { Sum = Sum + i; } printf("Sum of Natural Numbers = %d", Sum); return 0; }

The result of the above c program; as follows:

Please Enter any Integer Value :- 50 Sum of Natural Numbers = 1275

### C Program to find the Sum of First n Natural numbers using While Loop

#include<stdio.h> int main() { int Number, i = 1, Sum = 0; printf("\nPlease Enter any Integer Value :- "); scanf("%d", &Number); while(i <= Number) { Sum = Sum + i; i++; } printf("Sum of Natural Numbers = %d", Sum); return 0; }

The result of the above c program; as follows:

Please Enter any Integer Value :- 100 Sum of Natural Numbers = 5050

### C Program to find the Sum of First n Natural numbers using Function

/* * C program to find sum of n numbers using function */ #include<stdio.h> /*Write sum function that recieves the number * as an argument up to which you want to sum. * Return the total sum */ int sum(int num){ int i; int sum =0; //Loop through from 1 to num e.g. //if number is 3 so index will start from // 1 to 3 and sum will be as = 1+2+3 = 6 for(i=1; i<=num; ++i){ sum += i; // Also, this can be written as sum = sum +i; } return sum; } /* * Test sum of n numbers */ int main(){ int num =0; int result =0; printf("Enter number "); //Read the number up to which you want sum scanf("%d", &num); //call sum function that will return sum result = sum(num); printf("sum : %d ",result); return 0; }

The result of the above c program; as follows:

Enter number 50 sum : 1275

### C Program to find the Sum of First n Natural numbers using Recursion

#include <stdio.h> int addNumbers(int n); int main() { int num; printf("Enter a positive integer: "); scanf("%d", &num); printf("Sum = %d", addNumbers(num)); return 0; } int addNumbers(int n) { if (n != 0) return n + addNumbers(n - 1); else return n; }

The result of the above c program; as follows:

Enter a positive integer: 500 Sum = 125250