-conta-

From the Ancient Greek words for 30-90, which each ended in -κοντα (-konta). This ending might be ultimately related to Proto-Indo-European *déḱm̥ (“ten”), see e.g. τριάκοντα (triákonta).

-conta-

1. (organic chemistry, IUPAC) Combines with the prefixes for 3-9 to form complex prefixes referring to 30-90.

• -cosa- (forms prefixes for 21-29)