Here are three questions about Roman numerals that genuinely puzzle me!
First, why, in the twenty-first century, do we persist in using Roman numerals in particular contexts, such as the hours on clock or watch faces, and dates on buildings or at the end of a movie?
Second, in such a technological age, can anyone really justify the inclusion of Roman numerals in the statutory English primary mathematics curriculum and in the associated national assessment of mathematics?
Third, there’s something odd I’ve noticed recently about Roman numerals on clock and watch faces. It is important for teachers to be aware of this, because there are limited contexts for assessment items in Key Stage 1 and 2 national mathematics tests in this country, so clock and watch faces with Roman numerals turn up often.
In an early form of Roman numeration, the numbers we call ‘four’ and ‘nine’ would be represented by IIII and VIIII. A later development was to represent these more concisely as IV and IX, the convention being that when a letter representing a smaller value is written in front of another letter, then the value is to be subtracted, not added. So, XC would represent 90 (100 subtract 10). So, here’s what we have noticed: in most cases where Roman numerals are used on a clock or watch face, the four is written using the early system (IIII) and the nine is written using the later system (IX). Check this out and see if we are right. The question that puzzles me is, simply, why?