Recently Michael had a party and because it was his birthday he wanted a mathematical cake.
He ordered a cake in the shape of a cube, and had it completely iced (but of course he didn't have the underneath iced because that just isn't very sensible).
Michael cut every side of the cake into three equal pieces, giving him 27 slices of cake.
Michael wanted to eat all of the pieces of cake that had exactly 2 sides with icing.
So, how many pieces did that leave for his guests?