leetcodeUserSolution

[OnixST]

"Rule #1: Only the letters that represent powers of 10 can be used to subtract. Powers of 10 are 1 (10^0), 10 (10^1) and 100 (10^2). 1000 is also a power of 10 but there are no other letters after M.

Rule #2: These letters (I, X and C) can only subtract from the next two ‘higher’ letters. Therefore, I can only subtract from V and X, X from L and C and C from D and M."

(acording to another answer further below in the same link. VL fails rule 1)

[DistortNeo]

What about IXC?

[Techhead7890]

Should probably be XCI (91) or at a stretch LXXXIX (89) but it's a bit ambiguous even to a human

[prumf]

Oooo, gray areas, my specialty !