Bis is a Latin prefix or suffix designating the second instance of a thing, thus preceding ter. An example in recent modern usage is the ITU-T modem standard from the late 20th century, V.32bis. Bis can also refer to:
Pachelbel's Canon in D major, a piece of chamber music scored for three violins and basso continuo and originally paired with a gigue in the same key, experienced a tremendous surge in popularity during the 1970s.
You then have understood the an octave is a group of 8 white keys and 5 black keys giving the total of 13 keys per octave. You also understand that the 88 keys on the piano isnât just about the octaves, as the total keys in the octave are 85 and that there are 3 more keys to find.