It's even simpler than computer science. It's something a
human should know how to do! How do you figure out of a
number is even? It can be divided by two evenly! Then, all
the person needs to know is that mathemetics (and Perl) offer
the modulus operation (Perl uses the
character,
like C and C++) to return the remainder when a number is
divided by another. With these two pieces of information:
any human that can find patterns should be able to tell how
to determine whether a number is even or odd.