﻿ C Sharp - Show the sum of the series [ 9 + 99 + 999 + 9999...]

# C#: Display the sum of the series [ 9 + 99 + 999 + 9999 ...]

## C# Sharp For Loop: Exercise-21 with Solution

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

Sample Solution:-

C# Sharp Code:

using System;  // Importing necessary namespace

public class Exercise21  // Declaration of the Exercise21 class
{
public static void Main()  // Main method, entry point of the program
{
int n, i, t = 9;  // Declaration of variables n, i, t with initialization
int sum = 0;  // Variable to store the sum, initialized to 0

Console.Write("\n\n");  // Displaying new lines
Console.Write("Display the sum of the series [ 9 + 99 + 999 + 9999 ...]:\n");  // Displaying the purpose of the program
Console.Write("-----------------------------------------------------------");  // Displaying a separator
Console.Write("\n\n");

Console.Write("Input the number or terms :");  // Prompting the user to input the number of terms
n = Convert.ToInt32(Console.ReadLine());  // Reading the number of terms entered by the user

// Loop to generate the series and calculate the sum
for (i = 1; i <= n; i++)
{
sum += t;  // Adding the current value of t to the sum
Console.Write("{0}   ", t);  // Displaying the current value of t
t = t * 10 + 9;  // Generating the next value of t for the series
}

Console.Write("\nThe sum of the series = {0} \n", sum);  // Displaying the sum of the series
}
}

Sample Output:

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

Flowchart:

C# Sharp Code Editor:

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