Why? It's often a good idea to google for an answer. See the second result for "number of gas stations in the us", for example: http://www.infoplease.com/asked

Why? It's often a good idea to google for an answer. See the second result for "number of gas stations in the us", for example: http://www.infoplease.com/askeds/number-gas-stations-us-1995.html http://www.infoplease.com/askeds/number-gas-stations-us-1995... If you want the candidate to show his reasoning abilities by making good guesses based on reasonable assumptions, you should tell him to do so beforehand.