1. francisgranada Senior Member

    The Latin terms for the numerals 18 and 19 are duodeviginti and undeviginti. My question is, if there exists some explanation why aren't these two numerals formed "regularly" (e.g. octodecim, novendecim) ?

    Thanks in advance.
  2. Barsac Senior Member

    region of Bordeaux
    french - français
    Most probably, it is a trace of an old vigesimal numeric system (base 20). In french of France, we use the word quatre-vingt (four-twenty) for 80. The french-speaking Belgians say "huitante" or "octante" for the same number.

    Last edited by a moderator: May 26, 2012
  3. Joannes Senior Member

    Belgian Dutch
    Nope, septante (70), nonante (90), but quatre-vingt (80). I think the Swiss say octante..
  4. CapnPrep Senior Member

    Octodecim and novendecim/novemdecim do exist, although they are not the preferred forms in Classical Latin. I think the explanation is the same as why one might prefer to say "ten to six, quarter to six" instead of "five fifty, three quarters after five". Or if you're 19 years old, you might prefer to say "I'm almost 20" instead of "I'm in my teens". When you get close to the next round number, it is natural to use it as the new reference point, in anticipation.
  5. francisgranada Senior Member

    Thanks for the information, I dind't know that (I thought these forms were invented by me :D)
    Yes, this seems an acceptable explanation.
  6. Remember how the Romans formed their numerals too. 19 is not XVIIII but XIX. I have also seen XIIX for 18, but it may have been medieval rather than classical.
  7. CapnPrep Senior Member

    If these Roman numerals were truly a reflection of spoken Latin, I would expect to see IXX and IIXX for undeviginti and duodeviginti. These forms are attested, apparently, but I suspect that in many cases they are to be interpreted as unus et viginti and duo et viginti, i.e. 21 and 22, and not 19 and 18.

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