Where does “dieciocho” come from?

dieciocho (Chavacano) comes from Spanish dieciocho, from Spanish ocho, from Old Spanish ocho, from Old Spanish oito, from Latin octō, from Proto-Italic oktō, from Proto-Indo-European oḱtṓw, from Proto-Indo-European aḱ- — sharp, pointed; sharp, pointed, edgy; sharp,...

dieciocho (Chavacano): eighteen