C++ Program to Calculate Sum of Natural Numbers

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

To understand this example, you should have the knowledge of following C++ programming topics:

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.

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.

This program can also be done using recursion. Check out this article for calculating sum of natural numbers using recursion.