Meanwhile in Taiwan

the numbers in the national language here -- Mandarin Chinese -- follow the same pattern as with Japanese, though only "2" varies, depending on whether it modifies something or stands alone.

Taiwanese, a legacy of settlers from south China, is related to Mandarin Chinese, which was brought over by north Chinese officials and their armies, but the aboriginal languages aren't. I don't know how counting works there.

As I understand it, though, neither the Chinese languages nor Taiwan's aboriginal languages are related to Japanese.

Taiwanese friends have often told me, with certain pride, that their language (in this case mandarin) has no grammar to speak of. Rubbish of course, but, with very few changes in verbs for person or tense, or in nouns either, it's far simpler than the European languages I'm aware of.

So perhaps the variability in our numbers, with -teens and -ties and soixante-treizes, is just another aspect of how fiddly our languages are. Is there a fiddliness constant for each language?