There are a few theories detailed here: http://mentalfloss.com/article/24578/why-do-some-clocks-use-roman-numeral-iiii http://mentalfloss.com/article/24578/why

There are a few theories detailed here: http://mentalfloss.com/article/24578/why-do-some-clocks-use-roman-numeral-iiii http://mentalfloss.com/article/24578/why-do-some-clocks-use-... The reason I always heard is about ease of casting: it requires a more complex mold if 4 is written as IV instead of IIII.