Finding What Percentage a Plane is Covered By Pennies Touching Tangentially The question is the following:

Imagine covering an unlimited plane surface with a single layer of pennies, arranged so that each penny touches six others tangentially. What percentage of the plane is covered?

I can't seem to visually understand how a penny would touch six other pennies tangentially and I am, therefore, unable to understand how the plane is being covered in that pattern. Any help will be greatly appreciated. 

Draw a regular hexagon and put a penny in the middle and on each of the vertices. That gives you the covering you want.
