How do you figure out how many edges are in a hexagonal prism?

Answer 1

The hexagon at one end has 6 edges. The hexagon at the other end also has 6 edges. And then, there are 6 edges joining the two hexagons together. So, in all, there are 6+6+6 = 18 edges.

A prism with bases that are n-gons has 3*n edges.