I really wanted to require the solver to look it up which may have done that. I think this is probably a better representation:

The purpose of this kata is to encourage you to the review the evolution of the mathematical concept of numerals as this history is often taken for granted. Before Fibonacci, the Western world had a didn't advance much in mathematics simply because of the representation of numbers as Roman numerals.

I added a really big hint to the description text. Does that work for you?

Oh, the shame! The vicious goblins Copy & Paste have struck again :-)

Apologies, the test case was correct but the helping text in the "expected" part was a copy of the previous test case (the halfway). I've updated the text in the test case so it shows the correct expected value.

Thank you for spotting this :-)

Could you explain?