C program to add seven terms

#include <stdio.h>
#include <conio.h>
using namespace std ;
int main (  )
{
long double num , res , fres = 0 , fact = 1.0 ;
for ( num = 4.0 ; num <= 7.0 ; num++ )
{
fact = fact * num ;
res = num / fact ;
fres = fres + res ;
}
printf ( "the sum of given series is %.9Lf",fres);
return 0 ;
}