Why do some analog clocks with Roman numerals have '4' as 'IV,' while others have 'IIII'? This is one of those questions where no one seems to have a definitive answer, and probably no one ever will.

Thanks for your informative piece on the Roman numerals on the Tomb of the Unknowns. Now can you explain to me why the 4 on my watch is denominated by IIII instead of IV, a fact I had not noticed ...