I'm well out of my depth as I'm sure you can tell, but I think the phrase is porque no los dos?
Sources suggest dekam is Common Brythonic, but that doesn't mean the Old Welsh dec (now deg in Cymraeg) didn't come from Latin?
Wouldn't it be weird if mutation of words in Celtic/Brythonic and Latin happened identically over time. Of course the similarity through earlier common ancestry of counting words would facilitate such a move.
Thanks for your input though, my suggestion was supposed to be tentative as I know there are Latin loan words in Cymraeg from Old Welsh.
Do you know whence comes the support for "dekam" being well-established in Celtic via IE, is it largely based on phonemic evidence?
I don't know the exact etymology of this word in Celtic - just mentioning some other languages with a similar relationship to PIE, but not necessarily with the same degree of influence by Latin, for comparison.
I'm not sure what you mean by "mutation of the words happened identically over time"? The Latin for "ten" is "decem" - it didn't drop the "m" (hence also "decimus", "decimatio" etc). Most Romance languages did drop it eventually - but that came later, and in any case those languages wouldn't be in a position to influence Welsh.
FWIW, I don't think it would be all that surprising for related but diverged languages to evolve in a similar way. Sure, they may have developed some different laws governing those changes since the divergence - but they will also have some common laws from their shared ancestry. And there's "convergent evolution" of languages, as well. Although it would be interesting to find out if this particular change is really governed by some common rule, or some rule that independently arose in two different branches, or it's just a curious coincidence.
Sources suggest dekam is Common Brythonic, but that doesn't mean the Old Welsh dec (now deg in Cymraeg) didn't come from Latin?
Wouldn't it be weird if mutation of words in Celtic/Brythonic and Latin happened identically over time. Of course the similarity through earlier common ancestry of counting words would facilitate such a move.
Thanks for your input though, my suggestion was supposed to be tentative as I know there are Latin loan words in Cymraeg from Old Welsh.
Do you know whence comes the support for "dekam" being well-established in Celtic via IE, is it largely based on phonemic evidence?