Where does “ochaenta” come from?

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

Ancestry of “ochaenta”, step by step

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

ochaenta — Etymology, Origin & Word History | Etymology Explorer