In this example, you’ll learn to calculate the sum of natural numbers.


Positive integers 1, 2, 3, 4… are known as natural numbers.

This program takes a positive integer from user( suppose user entered n ) then, this program displays the value of 1+2+3+….+n.

The Sum can be calculated using the following formula:-


Example: Sum of Natural Numbers using loop

#include 
using namespace std;

int main()
{
    int n, sum = 0;

    cout << "Enter a positive integer: ";
    cin >> n;

    for (int i = 1; i <= n; ++i) {
        sum += i;
    }

    cout << "Sum = " << sum;
    return 0;
}

 

Output

Enter a positive integer: 50
Sum = 1275

 

This program assumes that user always enters positive number.

If user enters negative number, Sum = 0 is displayed and program is terminated.