Question

How to calculate the sum of series: 1/1! + 2/2! + 3/3! + 4/4! + ... N/N! in C#

Answer 1

using System;

class Program
{
    static int factorial(int n) {
        if (n <= 1) {
            return (1);
        } else {
            n = n * factorial(n - 1);
        }
 
        return n;
    }
    static void Main() {
        Console.WriteLine("Calculate the sum of series: 1/1! + 2/2! + 3/3! + 4/4! ... + N/N!");
        
        int N = 5;
        float sum = 0.0f;

        for (int i = 1; i <= N; i++) {
            sum += ((float) i / (float) factorial(i));
        }
        
        Console.WriteLine("sum = " + sum);
    }
}




/*
       
run:
       
Calculate the sum of series: 1/1! + 2/2! + 3/3! + 4/4! ... + N/N!
sum = 2.708333
   
*/

 

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