**In this example, you’ll learn to calculate the 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; }

**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.