## Sum of natural numbers in C++

We will take a number as input from the user and then determine the sum of natural numbers less than or equal to that numbers. Suppose a user gives the number 7. Then we will determine sum of,

1,  2,  3,  4,  5,  6 and 7.

We can make the program to determine the sum in several way. We will see some programs related to determining sum of natural numbers.

## Sum of natural numbers using formulae

We can easily make a program to find sum of natural numbers using the formulae bellow; Let’s see the C++ code for determining the sum of numbers using this formulae

``````// C++ program to find sum of natural numbers

#include <iostream>
using namespace std;

int main(){
int num, result;

cout <<"Enter an integer here : ";
cin >>num;

result = (num * (num + 1)) / 2;

cout <<"\nSum is = " << result <<endl;

return 0;
}
``````

### Output of sum of natural number program ## Sum of natural numbers using a loop

The bellow program will calculate the sum of natural numbers using a for loop. You can use other loop where the logic may be same or different if you have your own algorithm. Now, let’s see the program.

``````// sum of natural numbers using for loop

#include <iostream>
using namespace std;

int main(){
int c, num, result = 0;

cout <<"Enter the number here : ";
cin >>num;

for(c = 1; c <= num; ++c){
result = result + c;
}

cout <<"\nSum is = " <<result <<endl;

return 0;

}``````

### Output of this program:

``````Enter the number here : 30

Sum is = 465``````

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