Question

This is what I came up with:

#include <stdio.h>

int main (void)
{
  int n, i, j;
  float e = 1.0, nFact = 1.0;

  printf ("please enter the number");
  scanf ("%d", &n);

  for (i = 1; i <= n ; i++)
  {
    for (j = 1; j <= i; j++)
    {
      nFact *= j;
    }
    e = e + (1.0 / nFact);
  }

  printf ("The value of 'e' is : %f", e);
  return 0;
}

This is what I get from this code.
Input: 3
Output: 2.58333 (which is close to 2.6666…)

But for n=3, e should give 2.6666.. as a value.

Am I doing something wrong here? How can I get the proper output?

Answer 1

You are needlessly calculating the factorial in every iteration. Just replace the inner loop by nFact *= i;.

#include<stdio.h>

int main (void)
{
int n,i,j;
float e=1.0, nFact=1;

printf("please enter the number");
scanf("%d", &n);

for( i =1; i<= n ; i++)
{
    nFact*=i;
    e = e + (1.0/ nFact);
}

printf("The value of 'e' is : %f", e);

return 0;
}