C-bill. World War I. Pope Benedict XVI. Super Bowl XLIII. Final Fantasy II.
Although we normally use so-called Arabic numerals, their Roman counterparts are far from dead. In addition to the above examples, they're used to date movies; to identify book volumes such as encyclopedias; to mark off the front matter in books from the body, usually in lowercase (i, ii, iii, iv ...); for the cornerstones of buildings; for subsections in laws; etc. Once you start noticing them, you'll see them everywhere!
The Roman number system derived from the Etruscans of ancient Italy. Etruscan 1, 5 and 10 were written I, ? and X, becoming Roman I, V and X. The Etrusco-Roman symbols probably derived from tally sticks, as I discussed in a previous column on Arabic numerals. A notch across a stick became I, while every fifth notch was marked with a double cut (? or V) and the tenth notch was cross cut (X). (Or perhaps ten -- the number of digits on two hands -- came first and the ? or V was subsequently derived from half an X.)
The other Roman numerals -- L, C, D and M, for 50, 100, 500 and 1,000 -- don't lend themselves quite so readily to interpretation, but we're pretty sure that the Romans ultimately adopted C for centum (100) and M for mille (1,000), while the D may have come from demi-mille, half a thousand. The Roman system doesn't include a zero, which is probably why the Arabic system (which originated in India) was adopted so readily in the Middle Ages.
The system has the quirk of not being totally additive. An additive system would have the year 1944 as MDCCCCXXXXIIII, but instead it's usually shortened to MCMXLIV. The symbols C, X and I each precede a symbol of higher value, so the result is interpreted as 1,000 (M) plus 1,000-100 (CM) plus 50-10 (XL) plus 5-1 (IV).
So why do old clocks -- like the ones on 2nd Street in Old Town Eureka -- show four as IIII, not IV? Nine is shown as IX, so why isn't four written as IV? One explanation is that the pairs of numerals IV & VI and IX & XI are easily confused, but that IV and VI are doubly confusing because the IV is partly upside-down. Clockmakers responded to this ambiguity by using IIII for four.
Now we've got that straightened out, you can ask yourself: Why do clocks only go up to 12, when there are 24 hours in a day?
Barry Evans (firstname.lastname@example.org) wakes up each morning worrying how the Romans got to be so powerful without having a symbol for zero. He lives in Old Town Eureka.