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

• Difficulty Level : Basic
• Last Updated : 12 Jul, 2022

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```

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

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## Javascript

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Output:

`Sum: 2.70833`

Time Complexity: O(n)

Auxiliary Space: O(1), since no extra space has been taken.
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