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

02 Nov, 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
 
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
Java
Python3
C#
PHP
Javascript
// CPP program to print// the sum of series#include<bits/stdc++.h>using namespace std; // function to calculate// sum of given seriesdouble 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 Codeint main(){    double n = 5;    cout << "Sum: " << sumOfSeries(n);    return 0;}
// 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)>
# 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 = 5print("Sum: ", sumOfSeries(n)) # Code contributed by# Mohit Gupta_OMG <(0_o)>
// C# program to print the sum of seriesusing 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// PHP program to print// the sum of series // Function to calculate// sum of given seriesfunction sumOfSeries($num){    $res = 0; $fact = 1;    for ($i = 1; $i <= $num; $i++)    {        // fact variable store        // factorial of the i        $fact = $fact * $i;         $res = $res + ($i / $fact);    }    return ($res);} // Driver Code$n = 5;echo("Sum: " . sumOfSeries($n)); // This code is contributed by Ajit.?>
<script>// javascript program to print// the sum of series  function sumOfSeries(num){    var res = 0, fact = 1;    for (i = 1; i <= num; i++)    {             // fact variable store        // factorial of the i        fact = fact * i;        res = res + (i / fact);    }    return(res);} // Driver Codevar n = 5;document.write("Sum: " + sumOfSeries(n).toFixed(5)); // This code is contributed by Amit Katiyar</script>
Output:  
Sum: 2.70833
Time Complexity: O(n)
Auxiliary Space: O(1)This article is contributed by R_Raj. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. 
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