Here's another challenge I used to give to my students:
Let's begin with a bunch of little white cubes assembled into a big white cube. All the little white cubes are equal.
Then I decide to paint some of the faces of the big cube blue. Afterwards I break the big cube apart into the smaller ones.
Only $24$ of the smaller cubes remain completely white.
How many cubes formed the big one? How many big faces did I paint?
Usually I use this problem to show how much we can deduce with so little information.