# Sum of the series 5+55+555+.. up to n terms

• Difficulty Level : Basic
• Last Updated : 26 Mar, 2021

Find the sum up to n terms of the sequence: 5 + 55 + 555 + … up to n.
Examples :

```Input : 2
Output: 60

Input : 3
Output: 595```

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

Sum = 5 + 55 + 555 + …. n terms.
= 5/9[9 + 99 + 999 + …. n terms]
= 5/9[(10 – 1) + (100 – 1) + (1000 – 1) + … n terms]
= 5/9[10 + 100 + 1000 ….. – (1 + 1 + … 1)]
= 5/9[10(10n – 1)/(10 – 1) + (1 + 1 + … n times))
= 50/81(10n – 1) – 5n/9

Below is the Implementation to find the sum of given series:

## C++

 `// C++ program for sum of the``// series 5 + 55 + 555.....n``#include ``using` `namespace` `std;` `// function which return the``// the sum of series``int` `sumOfSeries(``int` `n)``{``    ``return` `0.6172 *``           ``(``pow``(10, n) - 1) -``                    ``0.55 * n;``    ` `}` `// Driver code``int` `main()``{``    ``int` `n = 2;``    ``cout << sumOfSeries(n);``    ``return` `0;``}`

## Java

 `// Java program for sum of the``// series 5 + 55 + 555.....n` `class` `GFG``{` `    ``// function which return the``    ``// the sum of series``    ``static` `int` `sumOfSeries(``int` `n)``    ``{``        ``return` `(``int``) (``0.6172` `*``                     ``(Math.pow(``10``, n) - ``1``) -``                                ``0.55` `* n);``    ``}``    ` `    ``// Driver code``    ``public` `static` `void` `main(String []args)``    ``{``        ``int` `n = ``2``;``        ``System.out.println(sumOfSeries(n));``    ``}``}` `// This code is contributed by UPENDRA BARTWAL.`

## Python3

 `# python program for sum of the``# series 5 + 55 + 555.....n` `def` `sumOfSeries(n):``    ``return` `(``int``) (``0.6172` `*``                 ``(``pow``(``10``, n) ``-` `1``) ``-``                        ``0.55` `*` `n)`  `# Driver Code``n ``=` `2``print``(sumOfSeries(n))` `# This code is contributed``# by Upendra Singh Bartwal`

## C#

 `// C# program for sum of the``// series 5 + 55 + 555.....n``using` `System;` `class` `GFG``{` `    ``// Function which return the``    ``// the sum of series``    ``static` `int` `sumOfSeries(``int` `n)``    ``{``        ``return` `(``int``)(0.6172 *``                    ``(Math.Pow(10, n) - 1) -``                                 ``0.55 * n);``    ``}``    ` `    ``// Driver code``    ``public` `static` `void` `Main()``    ``{``        ``int` `n = 2;``        ``Console.Write(sumOfSeries(n));``    ``}``}` `// This code is contributed by vt_m.`

## PHP

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## Javascript

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Output :

`60`

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