Dabbling in Ruby with Roman numerals.
To get a Roman numeral's Arabic equivalent, pass in a string:
RomanNumeral.new("MCMXCIX").arabic # => 1999
To get the Arabic equivalent of a Roman numeral, pass in an integer:
RomanNumeral.new(1999).roman # => "MCMXCIX"
Note the returned string is valid, and conforms to common/accepted usage patterns, but is not as minimalist as it could be. 1999, for example, could be expressed as
MIM. Roman numerals are computed according to commonly accepted formatting as outlined on Wikipedia: http://en.wikipedia.org/wiki/Roman_numerals