C++ Program to find Sum of Natural Numbers

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;
}

Output

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;
}

Output

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;
}

C++ Program 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;
}

Output

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;
}

Output

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;
}

Output

Please Enter the Number to find Sum of Natural Num  =  90

The Sum of Natural Number from 1 to 90 = 4095