factorial - Number of zeros not possible in $n!$

The number of zeros which are not possible at the end of the $n!$ is:

$a) 82 \quad\quad\quad b) 73 \quad\quad\quad c) 156 \quad\quad\quad d) \text{ none of these }$

I was trying to solve this problem. I know how to calculate the no of zeros in factorial but have no idea how to work out this problem quickly.