## How long is a lunar?

Gardner imagines that the inhabitants of the moon have a unit of distance called a “lunar”, a unit adopted because the moon’s surface area in square lunars is exactly equal to the volume of the moon in cubic lunars. If the diameter of the moon as 2160 miles, how many miles long is a lunar?

*Notes:* Think of the moon as a
sphere. The surface area of a
sphere is equal to `4 * pi * r ^2`

where r is its radius, and
the volume of a sphere is `(4 / 3) * pi * r^3`

.

### Solution

[[Solution is not quite complete yet!]]

### Try working it yourself

and so on.