Arthur, upon discovering that the mice wanted to remove his brain, because he was descended from the original inhabitants of Earth, not the Golgafrinchans, randomly drew makeshift scrabble tiles from Ford's bag, in an attempt to access the question the mice said was in there. The result revealed that the question that gives the answer '42', is indeed 'What is six times nine?' Given the random and unpredictable nature of life, the universe and everything, it makes perfect sense...or it doesn't. Whatever...
53 More Things To Do In Zero Gravity is a fictional book mentioned in The Hitchhiker's Guide to the Galaxy