# Find the sum of series 0.X + 0.XX + 0.XXX +… upto k terms

Last Updated : 23 Jun, 2022

Given a series of k terms, where ‘X’ is any value between 0-9 and ‘k’ is any positive integer. The task is to find the sum of given series:

0.X + 0.XX + 0.XXX +… up to ‘k’ terms

Examples

```Input: x = 4 , k = 10
Output : 4.39506

Input: x = 9 , k = 20
Output: 19.8889```

Explanation:

## C++

 `// C++ program for sum of the series``// 0.x,  0.xx, 0.xxx, ... upto k terms``#include ``using` `namespace` `std;` `// function which return the sum of series``float` `sumOfSeries(``int` `x, ``int` `k)``{``    ``return` `(``float``(x) / 81) * (9 * k - 1 + ``pow``(10, (-1) * k));``}` `// Driver code``int` `main()``{``    ``int` `x = 9;``    ``int` `k = 20;``    ``cout << sumOfSeries(x, k);` `    ``return` `0;``}`

## Java

 `// Java program for sum of the series ``// 0.x,  0.xx, 0.xxx, ... upto k terms ` `public` `class` `GFG {``    ` `    ``// function which return the sum of series ``    ``static` `float` `sumOfSeries(``int` `x, ``int` `k) ``    ``{ ``       ``float` `y = (``float``) (((``float``)(x) / ``81``) * (``9` `* k - ``1` `+ Math.pow(``10``, (-``1``) * k))); ``       ``return` `y ;``    ``} ``    ` `    ``// Driver code ``    ``public` `static` `void` `main (String args[]){``         ``int` `x = ``9``; ``         ``int` `k = ``20``; ``         ``System.out.println(sumOfSeries(x, k)); ``    ``}` `// This code is contributed by ANKITRAI1``}`

## Python3

 `#Python3 program for sum of series``#0.x, 0.xx, 0.xxx, ... upto k terms` `#function which return the sum of series ``def` `sumOfSeries(x, k):``    ` `    ``return` `(``float``(x)``/``81``) ``*` `(``9` `*` `k ``-` `1` `+` `10``*``*``( (``-``1``)``*``k ) )``    ` `#Driver code ``if` `__name__``=``=``'__main__'``:``    ``x ``=` `9``    ``k ``=` `20``    ``print``(sumOfSeries(x, k))``# This code is contributed by Shashank Sharma`

## C#

 `// C# program for sum of the series ``// 0.x, 0.xx, 0.xxx, ... upto k terms ``using` `System;` `class` `GFG ``{` `// function which return``// the sum of series ``static` `float` `sumOfSeries(``int` `x, ``int` `k) ``{ ``    ``float` `y = (``float``)(((``float``)(x) / 81) * ``              ``(9 * k - 1 + Math.Pow(10, (-1) * k))); ``    ``return` `y ;``} ` `// Driver code ``public` `static` `void` `Main ()``{``    ``int` `x = 9; ``    ``int` `k = 20; ``    ``Console.Write(sumOfSeries(x, k)); ``}``}` `// This code is contributed ``// by ChitraNayal`

## PHP

 ``

## Javascript

 ``

Output:
`19.8889`

Time Complexity: O(logk), where k is the given integer.

Auxiliary Space: O(1), no extra space is required, so it is a constant.

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