72/ 12 = 6 (piece)
In the middle of each face is a picture, and each face: 6*6=36 (sheets).
6 sides * * *: 6 * 6 * 6 = 2 16 (Zhang)
Unpainted bags are in the middle, 6 rows, 6 rows, 6 floors,1* *: 6 * 6 * 6 = 216 (PCs).