This is a deconstuction of matematikaadit's submission to therubygame challenge 5; 'Roman numerals. What are they good IV?'. The goal of the challenge is to take a string representing a roman numeral as input and return the integer that the numeral represents.
matematikaadit currently has the honour of the shortest (by character count) submission for this challenge. At first glance I didn't understand how it worked so I re-wrote and analyzed it until I did.
Making it readable
matematikaadit's original submission: