C++ Program to Calculate Sum of Natural Numbers

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 <iostream>
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;



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.


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