RNJ, that's exactly the train of thought that brought me to make this thread... after waffling about languages with different base systems over on facebook, I kind of wondered if these anomalous names are a hangover from days where a different base system was in use in whatever relevant culture(s).
sokkar, that stuff about the larger numbers reminded me of how peculiar it is that French has unique names for all its multiples of ten up to 100 with the exception of 80... which, if memory serves correctly (unlikely), is something a bit like saying four-twenties (quatre-vingts??!! that doesn't look right but I cba looking it up).
Eva, that book looks seriously interesting. I think I shall buy.
I also just remembered how funny it is that older people still sometimes use old school terms when talking about money, basically the expressions they used before the currency was decimalised here. Like "ten bob" (50p i think?) and things like that.