>But they do help clear up "halvtredsindstyve" and "halvfjerdsindstyve" >- if they mean "2½ times 20" and "3½ times 20", that makes even more >sense than something like "half-way along the way from the second to >the third times twenty". Archaic Russian had a similar system where _pol_- 'half' was prefixed to an ordinal (in the genitive, I believe): _polp'ata_ - 4.5 (half-fifth) _poltr'etyadtsat'_ - 25 (half-third-ten) _poltr'etyasta_ - 250 (half-third-hundred) The only words surviving until today are _poltora_ (1.5) and _poltorasta_ (150). Compare cardinal _dva_ 'two', but ordinal _vtoroy_ 'second'. Also, a base-3 or -9 system could make sense if you base it on the lunar month with 27 days. Russian had a special word for 27 - _trid'ev'at'_ (three-nine) - which looks like a base-9 number. A base-6 system could could be connected to the almost-30-days lunar month.