C++ Program to Calculate 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.

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.

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