Where does “kahdeksainen” come from?

kahdeksainen (Finnish) comes from Finnish kahdeksan, from Proto-Finnic kakteksa, from Proto-Finnic kakci, from Proto-Uralic *kakta.

Ancestry of “kahdeksainen”, step by step

StepLanguageWordMeaning
1Finnishkahdeksaneight
2Proto-Finnickakteksaeight
3Proto-Finnickakcitwo
4Proto-Uralic*kakta—
Every word from Proto-Uralic *kakta →Every word from Proto-Finnic kakci →Every word from Proto-Finnic kakteksa →