Calculate the sum of following series

Posted on Apr 7, 2020

C program to add first N terms of the following series. Value of N is entered by the user.
1/1! + 2/2! + 3/3! + 4/4! + …….

Program

#include<stdio.h>
#include<conio.h>
void main()
{
	int n, i, j;
	float sum=0;
	unsigned long long fact;

	printf("Enter the number of terms to be added\t:");
	scanf("%d",&n);

	for(i=1;i<=n;i++)
	{
		fact = 1;
		for(j=1;j<=i;j++)
		{
			fact = fact * j;
		}
		sum = sum + ((float)i/fact);
	}

	printf("Sum of first %d terms of the series ( 1/1! + 2/2! + 3/3! + ...) is\t: %f",n,sum);
	getch();	
}

Output

Enter the number of terms to be added   :6
Sum of first 6 terms of the series ( 1/1! + 2/2! + 3/3! + ...) is       : 2.716667