Dan Sulani <[log in to unmask]> writes:
>     Are there natlangs where there _are_ simple terms for things like
> "one and a half"? How about anyone's conlang(s)?

Not simple, but irregularly contracted in German (and Dutch):

  1    = ein-
  0,5  = ein halb
  2    = zwei
  2,5  = zweieinhalb
  1,5  = eineinhalb,
         but also and more commonly used:
           (I assume this is < anders + halb, where anders is
           'second' in an ancient interpretation)

What I find funny about 1,5 is that German regards it as plural:

   anderthalb     Bücher
   one-and-a-half books

but Dutch (and Plattdeutsch) regards it as singular:
   anderhalve     boek
   one-and-a-half book