Problem : What is the volume of a cube with edges of length one inch?

1 cubic inch.

Problem : Imagine a square, and another square in a plane perpendicular to the plane of the first square. If each square has side length one inch, what is the volume of the figure consisting of both squares?

The volume is zero. Two polygons can never be combined into a simple closed surface, and a simple closed surface is necessary to form the boundary of a solid that can have volume.

Problem : Into what kind of solid can all polyhedra be divided?