Leave the octave and think about the 7 notes.
Basic notes, A,B,C,D,E,F and G and probably flats/sharps associated to those.
You said 88 keys = 88 notes but they are just same basic notes,one of those 7 +sharp/flat.
You said 88 keys = 88 notes but they are just same basic notes,one of those 7 +sharp/flat.