Or its sibling: a genie grants both a mathematician and an engineer their greatest desire to be located at the end of the room given that each step they take to

Or its sibling: a genie grants both a mathematician and an engineer their greatest desire to be located at the end of the room given that each step they take towards it is half the distance than their last. The mathematician throws his arms up and yells "Impossible! I'll never reach it," and storms out of the room. The engineer just smiles and says to the genie, "I can get close enough."