Write a C++ Program to find the sum of natural numbers from 1 to n. This C++ program allows you to enter the maximum number to calculate the sum of natural numbers. Next, we used the while loop to iterate from 1 to n by incrementing the i value. Within the loop, we are adding each value of i to the sum and prints the sum.
#include<iostream> using namespace std; int main() { int number, i = 1, sum = 0; cout << "\nPlease Enter the Number to find Sum of Natural Num = "; cin >> number; while( i <= number) { sum = sum + i; i++; } cout << "\nThe Sum of Natural Number from 1 to " << number << " = " << sum; return 0; }
Please Enter the Number to find Sum of Natural Num = 10
The Sum of Natural Number from 1 to 10 = 55
C++ Sum of Natural Numbers example code using Do While Loop.
#include<iostream> using namespace std; int main() { int number, i = 1, sum = 0; cout << "\nPlease Enter the Number to find Sum of Natural Num = "; cin >> number; do { sum = sum + i; i++; } while( i <= number); cout << "\nThe Sum of Natural Number from 1 to " << number << " = " << sum; return 0; }
Please Enter the Number to find Sum of Natural Num = 20
The Sum of Natural Number from 1 to 20 = 210
C++ Program to find Sum of Natural Numbers using For Loop
Here, we added one more cout statement inside the for loop: cout << “\n Iteration = ” << i << “, i = ” << i << “, sum = “<< sum << ” + ” << i << ” = “<< sum + i;. This statement helps you to understand the program in iteration wise.
#include<iostream> using namespace std; int main() { int number, i = 1, sum = 0; cout << "\nPlease Enter the Number to find Sum of Natural Num = "; cin >> number; for(i = 1; i <= number; i++) { cout << "\n Iteration = " << i << ", i = " << i << ", sum = "<< sum << " + " << i << " = "<< sum + i; sum = sum + i; } cout << "\nThe Sum of Natural Number from 1 to " << number << " = " << sum; return 0; }

This Program helps to calculate the Sum of Natural Numbers using Functions.
#include<iostream> using namespace std; int sumOfNaturalNumbers(int number) { int sum = 0; for(int i = 1; i <= number; i++) { sum = sum + i; } return sum; } int main() { int number; cout << "\nPlease Enter the Number to find Sum of Natural Num = "; cin >> number; int sum = sumOfNaturalNumbers(number); cout << "\nThe Sum of Natural Number from 1 to " << number << " = " << sum; return 0; }
Please Enter the Number to find Sum of Natural Num = 25
The Sum of Natural Number from 1 to 25 = 325
C++ Program to Calculate the Sum of Natural Numbers using a Math formula
As we all know, the mathematical formula to calculate the sum of natural numbers = number * (number + 1) / 2).
#include<iostream> using namespace std; int sumOfNaturalNumbers(int number) { if(number == 0) { return number; } else { return (number * (number + 1) / 2); } } int main() { int number; cout << "\nPlease Enter the Number to find Sum of Natural Num = "; cin >> number; int sum = sumOfNaturalNumbers(number); cout << "\nThe Sum of Natural Number from 1 to " << number << " = " << sum; return 0; }
Please Enter the Number to find Sum of Natural Num = 50
The Sum of Natural Number from 1 to 50 = 1275
C++ Program to Calculate the Sum of Natural Numbers using Recursion.
#include<iostream> using namespace std; int sumOfNaturalNumbers(int number) { if(number == 0) { return number; } else { return (number + sumOfNaturalNumbers(number - 1)); } } int main() { int number; cout << "\nPlease Enter the Number to find Sum of Natural Num = "; cin >> number; int sum = sumOfNaturalNumbers(number); cout << "\nThe Sum of Natural Number from 1 to " << number << " = " << sum; return 0; }
Please Enter the Number to find Sum of Natural Num = 90
The Sum of Natural Number from 1 to 90 = 4095