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Sum of the sequence 2, 22, 222, ………
• Difficulty Level : Medium
• Last Updated : 25 Apr, 2018

Find the sum of the following sequence : 2, 22, 222, ……… to n terms.
Examples :

```Input : 2
Output: 1.9926

Input : 3
Output: 23.9112
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

A simple solution is to compute terms one by one and add to the result.

The above problem can be efficiently solved using the following formula:

## C++

 `// CPP program to find sum of series ` `// 2, 22, 222, .. ` `#include ` `using` `namespace` `std; ` ` `  `// function which return the ` `// the sum of series ` `float` `sumOfSeries(``int` `n) ` `{ ` `    ``return` `0.0246 * (``pow``(10, n) - 1 - (9 * n)); ` `} ` ` `  `// driver code ` `int` `main() ` `{ ` `    ``int` `n = 3; ` `    ``cout << sumOfSeries(n); ` `    ``return` `0; ` `} `

## Java

 `// JAVA Code for Sum of the ` `// sequence 2, 22, 222,... ` `import` `java.util.*; ` ` `  `class` `GFG { ` `     `  `    ``// function which return the ` `    ``// the sum of series ` `    ``static` `double` `sumOfSeries(``int` `n) ` `    ``{ ` `        ``return` `0.0246` `* (Math.pow(``10``, n) ` `                            ``- ``1` `- (``9` `* n)); ` `    ``} ` `     `  `    ``/* Driver program */` `    ``public` `static` `void` `main(String[] args)  ` `    ``{ ` `         ``int` `n = ``3``; ` `         ``System.out.println(sumOfSeries(n)); ` `    ``} ` `} ` ` `  `// This code is contributed by Arnav Kr. Mandal. `

## Python3

 `# Python3 code to find  ` `# sum of series ` `# 2, 22, 222, .. ` `import` `math ` ` `  `# function which return  ` `# the sum of series ` `def` `sumOfSeries( n ): ` `    ``return` `0.0246` `*` `(math.``pow``(``10``, n) ``-` `1` `-` `(``9` `*` `n)) ` `     `  `# driver code ` `n ``=` `3` `print``( sumOfSeries(n)) ` ` `  `# This code is contributed by "Sharad_Bhardwaj". `

## C#

 `// C# Code for Sum of the ` `// sequence 2, 22, 222,... ` `using` `System; ` ` `  `class` `GFG { ` `     `  `    ``// Function which return the ` `    ``// the sum of series ` `    ``static` `double` `sumOfSeries(``int` `n) ` `    ``{ ` `        ``return` `0.0246 * (Math.Pow(10, n) ` `                           ``- 1 - (9 * n)); ` `    ``} ` `     `  `    ``// Driver Code ` `    ``public` `static` `void` `Main()  ` `    ``{ ` `        ``int` `n = 3; ` `        ``Console.Write(sumOfSeries(n)); ` `    ``} ` `} ` ` `  `// This code is contributed by vt_m. `

## PHP

 ` `

Output :

```23.9112
```

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