Quiz Answer

Each cube must bear a 0, 1, and 2. This leaves only six faces for the remaining seven digits, but fortunately the same face can be used for 6 and 9, depending on how the cube is turned. The picture shows 3, 4, and 5 on the right cube, and therefor its hidden faces must be 0, 1, and 2. On the left cube one can see 1 and 2, and so its hidden faces must be 0, 6 or 9, 7, and 8.