Where does “octāgintā” come from?

octāgintā (Latin) comes from Proto-Indo-European oktōḱomt, from Proto-Indo-European oḱto(w)-dḱomt — eight-ten.

Ancestry of “octāgintā”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	oktōḱomt	—
2	Proto-Indo-European	oḱto(w)-dḱomt	eight-ten

octāgintā — Etymology, Origin & Word History | Etymology Explorer