How do you answer Fermi questions?

Answer

Fermi questions, aka order of magnitude questions ask you to express something numerically that can only be vaguely guesstimated. An example would be how many golf balls does it take to fill the Atlantic Ocean? or how many quarters would it take to cover the surface of the Earth. Because the answers are simply a wild estimation, they are expressed by a power of ten. Say for example you calculated an answer to be 28374738, this would be the equivalent of 2.83 X 10^7, or in a Fermi question, expressed as an answer of 7. The easiest way to go about solving a Fermi question is by breaking it down to as many conversions that you are fairly certain of as possible.