Dictionary entry

δεκαπέντε

G. Abbott-Smith's A Manual Greek Lexicon of the New Testament

δεκα-πέντε

[in LXX: Ex 27:15, I Mac 10:40, al.;]

late form of πεντεκαίδεκα, fifteen: Jo 11:18, Ac 27:5, WH, mg., ib. 28, Ga 1:18.†