A proposed new $5 coin is called the foonie. The foonie's two faces are identical and each has area 5 cm2. The thickness of the foonie is 0:5 cm. How many foonies are in a stack that has a volume of 50 cm3?

The volume of a foonie will be the area of its face times its thickness: 5 cm^{2} x 0.5 cm = 2.5 cm^{3}.

To find the number of foonies in a stack of volume 50 cm^{3}, we can divide the volume of the stack

by the volume of each foonie: 50 cm^{3} / 2.5 cm^{3} = 20 foonies