Phrases from The Hitchhiker's Guide to the Galaxy - Wikipedia, the free encyclopedia: In the radio series and the first novel, a group of hyper-intelligent pan-dimensional beings demand to learn the Answer to the Ultimate Question of Life, The Universe, and Everything from the supercomputer, Deep Thought, specially built for this purpose. It takes Deep Thought 7½ million years to compute and check the answer, which turns out to be 42. Deep Thought points out that the answer seems meaningless because the beings who instructed it never actually knew what the Question was.
When asked to produce The Ultimate Question, Deep Thought says that it cannot; however, it can help to design an even more powerful computer that can...
"Six by nine. Forty two."
"That's it. That's all there is."
Six times nine is actually fifty-four. The program on the "Earth computer" should have run correctly, but the unexpected arrival of the Golgafrinchans on prehistoric Earth caused input errors into the system—computing (because of the garbage in, garbage out rule) the wrong question—the question in Arthur's subconscious being invalid all along."I always thought something was fundamentally wrong with the universe"
Narrator: There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.
Some readers noticed that 613 × 913 = 4213 (using base 13). Douglas Adams later joked about this observation, saying, "I may be a sorry case, but I don't write jokes in base 13."There is another theory, which states that this has already happened.
In Life, the Universe and Everything, Prak, a man who knows all that is true, confirms that 42 is indeed The Answer, and confirms that it is impossible for both The Answer and The Question to be known in the same universe as they will cancel each other out and take the Universe with them—to be replaced by something even more bizarre (as described in the first theory) and that it may have already happened (as described in the second).