I see what you mean now. That's 19 with additive Roman numerals only, right? And for good measure, you don't even have to rearrange the digits, you can just ord

I see what you mean now. That's 19 with additive Roman numerals only, right? And for good measure, you don't even have to rearrange the digits, you can just order them as DCCCCLXXXXVIIII and cover the unused ones with a cloth. With subtractive Roman numerals, you can get away with just 17 digits, but you lose the feature of not having to rearrange them. Edit: actually, how did we get 19 here? I agreed at first, but my number above is just 15 digits.