Related Articles

# Program to find the sum of a Series 1/1! + 2/2! + 3/3! + 4/4! +…….+ n/n!

• Difficulty Level : Basic
• Last Updated : 25 Mar, 2021

You have been given a series 1/1! + 2/2! + 3/3! + 4/4! +…….+ n/n!, find out the sum of the series till nth term.
Examples :

```Input :n = 5
Output : 2.70833

Input :n = 7
Output : 2.71806```

Attention reader! Don’t stop learning now. Get hold of all the important mathematical concepts for competitive programming with the Essential Maths for CP Course at a student-friendly price. To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

A simple solution is to one by one computer terms. For every term, find its corresponding factorial value.
An efficient solution is to do factorial computations in same loop.

## CPP

 `// CPP program to print``// the sum of series``#include``using` `namespace` `std;` `// function to calculate``// sum of given series``double` `sumOfSeries(``double` `num)``{``    ``double` `res = 0, fact = 1;``    ``for` `(``int` `i = 1; i <= num; i++)``    ``{``        ``// fact variable store``        ``// factorial of the i``        ``fact = fact * i;` `        ``res = res + (i / fact);``    ``}``    ``return``(res);``}` `// Driver Code``int` `main()``{``    ``double` `n = 5;``    ``cout << ``"Sum: "` `<< sumOfSeries(n);``    ``return` `0;``}`

## Java

 `// Java program to print``// the sum of series` `import` `java.io.*;``import` `java.lang.*;` `class` `GFG``{``    ``public` `static` `double` `sumOfSeries(``double` `num)``    ``{``        ``double` `res = ``0``, fact = ``1``;``        ``for` `(``int` `i = ``1``; i <= num; i++)``        ``{``            ``// fact variable store``            ``// factorial of the i``            ``fact = fact * i;` `            ``res = res + (i / fact);``        ``}``        ``return``(res);``    ``}` `    ``// Driver Code``    ``public` `static` `void` `main (String[] args)``    ``{``        ``double` `n = ``5``;``        ``System.out.println(``"Sum: "` `+ sumOfSeries(n));``    ``}``}` `// This code is contributed by``// Mohit Gupta_OMG <(0_o)>`

## Python3

 `# Python code to find smallest K-digit ``# number divisible by X` `def` `sumOfSeries(num):``    ` `    ``# Computing MAX``    ``res ``=` `0``    ``fact ``=` `1``    ` `    ``for` `i ``in` `range``(``1``, num``+``1``):``        ``fact ``*``=` `i``        ``res ``=` `res ``+` `(i``/` `fact)``        ` `    ``return` `res``    `  `n ``=` `5``print``(``"Sum: "``, sumOfSeries(n))` `# Code contributed by``# Mohit Gupta_OMG <(0_o)>`

## C#

 `// C# program to print the sum of series``using` `System;` `class` `GFG``{``    ``public` `static` `float` `sumOfSeries(``double` `num)``    ``{``        ``float` `res = 0, fact = 1;``        ``for` `(``int` `i = 1; i <= num; i++)``        ``{``            ``// fact variable store``            ``// factorial of the i``            ``fact = fact * i;` `            ``res = res + (i / fact);``        ``}``        ``return``(res);``    ``}` `    ``// Driver Code``    ``public` `static` `void` `Main ()``    ``{``        ``double` `n = 5;``        ``Console.Write(``"Sum: "` `+ sumOfSeries(n));``    ``}``}` `// This code is contributed by vt_m.`

## PHP

 ``

## Javascript

 ``

Output:

`Sum: 2.70833`

Time Complexity: O(n)
This article is contributed by R_Raj. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.