Suppose you stack three identical number cubes. It is possible to have no sides, two sides, or all four sides of the stack showing all the same number. (Note that if one side of a stack shows all the same number, then the opposite side must as well.) How many ways are there to stack three standard number cubes so that at least two sides of the stack show all the same number? If you can rotate a stack so that it is the same as another, count them as the same arrangement. Explain your solution.