NOTE: Nine had to get his Cube, or the the song wouldn't rhyme.
Lyrics to hear it out right: 6 by 6 by 6 is the next one in line, 216! 7 by 7 by 7 is 343! 8 by 8 by 8's not a chore when it equals 512! And Nine by Nine.... equals! There's so much more to explore! 729!