C++ Exercises: Calculate the series (1) + (1+2) + (1+2+3) + (1+2+3+4) + ... + (1+2+3+4+...+n)

Last update on December 20 2024 12:23:01 (UTC/GMT +8 hours)

Write a program in C++ to calculate the series (1) + (1+2) + (1+2+3) + (1+2+3+4) + ... + (1+2+3+4+...+n).

Visual Presentation:

Sample Solution :-

C++ Code :

#include <iostream> // Including the input/output stream header file

using namespace std; // Using the standard namespace to avoid writing std::

int main() // Start of the main function
{
    int i, j, n, sum = 0, tsum; // Declaration of integer variables 'i', 'j', 'n', 'sum', and 'tsum'

    // Display a message to find the sum of the series (1) + (1+2) + (1+2+3) + (1+2+3+4) + ... + (1+2+3+4+...+n)
    cout << "\n\n Find the sum of the series (1) + (1+2) + (1+2+3) + (1+2+3+4) + ... + (1+2+3+4+...+n):\n";
    cout << "------------------------------------------------------------------------------------------\n";

    // Prompt the user to input the value for the nth term of the series
    cout << " Input the value for nth term: ";
    cin >> n; // Read the value entered by the user

    for (i = 1; i <= n; i++) // Outer loop to iterate from 1 to 'n'
	{
        tsum = 0; // Initializing 'tsum' to 0 for each iteration of the outer loop

        for (j = 1; j <= i; j++) // Inner loop to calculate the partial sums for each term of the series
		{
            sum += j; // Add 'j' to 'sum'
            tsum += j; // Add 'j' to 'tsum' for the current term

            cout << j; // Display the current value of 'j'

            if (j < i) // Condition to print '+' for all values of 'j' except the last one in each term
			{
                cout << "+"; // Display '+'
            }
        }

        cout << " = " << tsum << endl; // Display the calculated partial sum for the current term
    }

    // Display the total sum of the series
    cout << " The sum of the above series is: " << sum << endl;

    return 0; // Indicating successful completion of the program
}

Sample Output:

 Find the sum of the series (1) + (1+2) + (1+2+3) + (1+2+3+4) + ... + (
1+2+3+4+...+n):                                                        
-----------------------------------------------------------------------
-------------------                                                    
 Input the value for nth term: 5                                       
1 = 1                                                                  
1+2 = 3                                                                
1+2+3 = 6                                                              
1+2+3+4 = 10                                                           
1+2+3+4+5 = 15                                                         
 The sum of the above series is: 35 

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