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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 the 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.