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 until my XII-year old son pointed it out to me.

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       — Jim Blair, Oakton, Va.

       There are nearly as many theories as there are numbers on a clock face.

       One doubtful theory holds that ancient Romans were reluctant to use “IV” for 4 because those letters start the Latin word for the god Jupiter: IVPPITER. They didn’t want to anger the big guy by abbreviating his name on a sundial. (As you’ll see below, there’s a reason that’s bogus.)

       Another fanciful theory blames French monarch Charles V. American newspapers of the late 19th and early 20th century loved to trot out this hoary tale. Supposedly, in 1370 a clockmaker named Henry Vick (or Henri de Vic) built a masterful clock for his majesty.

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       The king had a reputation for being a nitpicker. The clock was perfect, but Charles had to live up to his billing. The nit he chose to pick was the number 4, which Vick had rendered as IV.

       “The figure for 4 o’clock should be four I’s instead of IV,” Charles said.

       The clockmaker pointed out that the king was wrong. The 4 should be IV.

       “I am never wrong! Take this dial away and correct your mistake!”

       And after that, all clocks had IIII instead of IV.

       “What a story!” a clockmaker told a reporter for the Chicago Daily News in 1927. “A cheap explanation for the vulgar hordes!”

       This clockmaker went on to provide a more technical explanation. On early clocks, it was the face that turned, not the hands, he said. A fixed arrow pointed up and the numbered face rotated, the topmost number indicating the hour.

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       According to this theory, the face turned best if had an even weight around its circumference. For 4, the four strokes of IIII balanced the face better than the three strokes of IV.

       This article is the only place Answer Man has seen that theory, but it’s similar to another: that using IIII allowed the 12 numerals to be divided into three similar groups of four. The first group uses only I’s: I, II, III, IIII. The second uses V’s and I’s: V, VI, VII, VIII. The third uses X’s and I’s: IX, X, XI, XII.

       This may be an after-the-fact explanation, but it’s akin to another: that IIII balances better visually with VIII across the face. This is an aesthetic explanation. The face just looks more symmetrical that way. That’s the theory favored by most horologists.

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       Latin scholars point out that the ancient Romans themselves didn’t use IV for 4; they used IIII. As Rutgers classics professor T. Corey Brennan pointed out last week, the convention to not use more than three of the same letters in a row is modern. The subtractive method — where you subtract the first, smaller number from the larger one that comes after it — came about in the Middle Ages.

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       A Wall Street Journal article from MMIV — er, 2004 — noted that some luxury watchmakers had started bucking the IIII trend, favoring IV.

       The clock face of Washington’s Old Post Office tower uses IIII, but not all famous clocks do. The clock at the Houses of Parliament in London — called Big Ben (though that’s the name of the bell inside) — uses IV.

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       So, to sum up: No one knows for sure why clocks have IIII. It may have started for aesthetics and continues because of tradition.

       But here’s something that blew Answer Man’s mind, something he’d never noticed before, though his house is full of ticking, whirring and chiming mechanical timepieces: The Roman numerals on most clocks are centripetal, that is, they are not horizontal but point toward the center.

       The 6 at the bottom of the face isn’t VI but IΛ. Cool, huh?

       Questions, please

       Curious about something in the Washington area? Perhaps Answer Man can help. Send your query to answerman@washpost.com.

       Time for Helping Hand

       We’re halfway through our Helping Hand campaign to raise $250,000 for three Washington charities that address hunger and homelessness: Bread for the City, Friendship Place and Miriam’s Kitchen.

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       Thank you.

       Twitter: @johnkelly

       For previous columns, visit washingtonpost.com/john-kelly.