# Sum of series 8/10, 8/100, 8/1000, 8/10000. . . till N terms

Given a positive integer **n**, the task is to find the sum of series

8/10 + 8/100 + 8/1000 + 8/10000. . . till

Nthterm

**Examples:**

Input:n = 3Output:0.888

Input:n = 5Output:0.88888

**Approach:**

The total sum till **nth** term of the given G.P. series can be generalized as-

The above formula can be derived following the series of steps-

The given G.P. series

Here,

Thus, using the sum of G.P. formula for r<1

Substituting the values of a and r in the above equation

**Illustration:**

Input:n = 3Output:0.888Explanation:

S_{n}=\frac{8}{9}(1-(\frac{1}{10})^{3})

= 0.888 * 0.999

= 0.888

Below is the implementation of the above problem-

## C++

`// C++ program to implement` `// the above approach` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Function to calculate sum of` `// given series till Nth term` `double` `sumOfSeries(` `double` `N)` `{` ` ` `return` `(8 * ((` `pow` `(10, N) - 1) / ` `pow` `(10, N))) / 9;` `}` `// Driver code` `int` `main()` `{` ` ` `double` `N = 5;` ` ` `cout << sumOfSeries(N);` ` ` `return` `0;` `}` |

## Java

`// Java program to implement` `// the above approach` `import` `java.util.*;` `public` `class` `GFG` `{` ` ` ` ` `// Function to calculate sum of` ` ` `// given series till Nth term` ` ` `static` `double` `sumOfSeries(` `double` `N)` ` ` `{` ` ` `return` `(` `8` ` ` `* ((Math.pow(` `10` `, N) - ` `1` `) / Math.pow(` `10` `, N)))` ` ` `/ ` `9` `;` ` ` `}` ` ` `// Driver code` ` ` `public` `static` `void` `main(String args[])` ` ` `{` ` ` `double` `N = ` `5` `;` ` ` `System.out.print(sumOfSeries(N));` ` ` `}` `}` `// This code is contributed by Samim Hossain Mondal.` |

## Python3

`# Python code for the above approach` `# Function to calculate sum of` `# given series till Nth term` `def` `sumOfSeries(N):` ` ` `return` `(` `8` `*` `(((` `10` `*` `*` `N) ` `-` `1` `) ` `/` `(` `10` `*` `*` `N))) ` `/` `9` `;` `# Driver code` `N ` `=` `5` `;` `print` `(sumOfSeries(N));` `# This code is contributed by gfgking` |

## C#

`// C# program to implement` `// the above approach` `using` `System;` `class` `GFG` `{` ` ` ` ` `// Function to calculate sum of` ` ` `// given series till Nth term` ` ` `static` `double` `sumOfSeries(` `double` `N)` ` ` `{` ` ` `return` `(8` ` ` `* ((Math.Pow(10, N) - 1) / Math.Pow(10, N)))` ` ` `/ 9;` ` ` `}` ` ` `// Driver code` ` ` `public` `static` `void` `Main()` ` ` `{` ` ` `double` `N = 5;` ` ` `Console.WriteLine(sumOfSeries(N));` ` ` `}` `}` `// This code is contributed by ukasp.` |

## Javascript

`<script>` ` ` `// JavaScript code for the above approach` ` ` `// Function to calculate sum of` ` ` `// given series till Nth term` ` ` `function` `sumOfSeries(N) {` ` ` `return` `(8 * ((Math.pow(10, N) - 1) / Math.pow(10, N))) / 9;` ` ` `}` ` ` `// Driver code` ` ` `let N = 5;` ` ` `document.write(sumOfSeries(N));` ` ` `// This code is contributed by Potta Lokesh` ` ` `</script>` |

**Output**

0.88888

**Time Complexity: **O(1) **Auxiliary Space: **O(1)