The Hitchhiker's Guide to the Galaxy  

This is the story of ‘The Hitch-Hiker’s Guide to the Galaxy’. Perhaps the most remarkable, certainly the most successful book, ever to come out of the great publishing corporations of Ursa Minor. More popular than ‘The Celestial Homecare Omnibus’, better selling than ‘Fifty-Three More Things To Do In Zero Gravity’, and more controversial than Oolon Colluphid’s trilogy of philosophical blockbusters: ‘Where God Went Wrong’, ‘Some More Of God’s Greatest Mistakes’, and ‘Who Is This God Person Anyway?’. And in many of the more relaxed civilizations on the outer eastern rim of the galaxy, the ‘Hitch Hiker’s Guide’ has already supplanted the great ‘Encyclopaedia Galactica’ as the standard repository of all knowledge and wisdom. Because although it has many omissions, contains much that is apocryphal - or at least wildly inaccurate - it scores over the older, more pedestrian work in two important ways: first, it is slightly cheaper, and second, it has the words ‘Don’t Panic’ inscribed in large, friendly letters on the cover. To tell the story of the book, it’s best to tell the story of some of the minds behind it. A human, from the planet Earth, was one of them, though as our story opens, he no more knows his destiny than a tea-leaf knows the history of the East India Company. His name is Arthur Dent, he is a six-foot tall ape descendant, and someone is trying to drive a bypass through his home. --incipit

The number 42 is, in The Hitchhiker's Guide to the Galaxy by Douglas Adams, the "Answer to the Ultimate Question of Life, the Universe, and Everything", calculated by an enormous supercomputer named Deep Thought over a period of 7.5 million years. Unfortunately, no one knows what the question is. Thus, to calculate the Ultimate Question, a special computer the size of a small planet was built from organic components and named "Earth". The Ultimate Question "What do you get when you multiply six by nine" was found by Arthur Dent and Ford Prefect in the second book of the series, The Restaurant at the End of the Universe. This appeared first in the radio play and later in the novelization of The Hitchhiker's Guide to the Galaxy.