# C++ Exercises: Display the sum of the specified series

## C++ For Loop: Exercise-23 with Solution

Write a program in C++ to display the sum of the series [ 9 + 99 + 999 + 9999 ...].

**Visual Presentation:**

**Sample Solution**:-

**C++ Code :**

```
#include <iostream> // Including input-output stream header
using namespace std; // Using standard namespace to avoid writing std::
int main() // Start of the main function
{
long int n, i, t = 9; // Declaration of long integer variables 'n' (number of terms), 'i' (loop counter), 't' (initial value of 9)
int sum = 0; // Declaration of integer variable 'sum' initialized to 0 (to store the sum)
cout << "\n\n Display the sum of the series [ 9 + 99 + 999 + 9999 ...]\n"; // Displaying a message on the console
cout << "-------------------------------------------------------------\n";
cout << " Input number of terms: "; // Prompting the user to input the number of terms
cin >> n; // Reading the input value as the number of terms
for (i = 1; i <= n; i++) // Loop to calculate 'n' terms of the series
{
sum += t; // Adding 't' (current term) to the sum
cout << t << " "; // Displaying the current term of the series
t = t * 10 + 9; // Generating the next term of the series by multiplying 't' by 10 and adding 9
}
cout << "\n The sum of the series = " << sum << endl; // Displaying the sum of the series
}
```

Sample Output:

Display the sum of the series [ 9 + 99 + 999 + 9999 ...] ------------------------------------------------------------- Input number of terms: 5 9 99 999 9999 99999 The sum of the sarise = 111105

**Flowchart: **

**C++ Code Editor:**

** Contribute your code and comments through Disqus.**

**Previous:** Write a program in C++ to display the n terms of harmonic series and their sum.

**Next:** Write a program in C++ to display the sum of the series [ 1+x+x^2/2!+x^3/3!+....].

**What is the difficulty level of this exercise?**

**It will be nice if you may share this link in any developer community or anywhere else, from where other developers may find this content. Thanks.**

https://www.w3resource.com/cpp-exercises/for-loop/cpp-for-loop-exercise-23.php

**Weekly Trends and Language Statistics**- Weekly Trends and Language Statistics