If the instructor is giving an assignment to write code in Perl, I would expect them to be aware of all Perl code that is commonly known to be available on the internet(i.e. CPAN). Assigning a problem where a known solution is posted on CPAN seems absurd to me. A better approach in my mind would be to say: study the Math::Roman module that can be found on CPAN and write a program that shows me you know how it works.

If a person enjoys reinventing the wheel, they can do it on their own time, and more power to them. Making that a classroom assignment would be offensive to me.