Don't forget "the universe and everything." At least, a I think that's the exact quote. Something like that anyway. Great books. Need to read them again.
Deep Thought was commissioned to answer the "Ultimate Answer to Life, the Universe and Everything." The answer was 42. Then Deep Thought laid out the plans for an even bigger supercomputer which would give the "Ultimate Quesiton to LIfe, the Universe, and Everything."
However, moments before Earth was due to give its answer, it was destroyed by a Vogon work crew to make for a new interstellar bypass with only two humans escaping, Trish McMillan (aka Trillian) and Arthur Dent. At one point, Arthur and Ford Prefect end up on a prehistoric Earth where he has to pull scrabble tiles from a bag, and it's determined the Ultimate Question is "What is six times nine?"
(from memory, so I'm sorry if I got Trillian's Earth name incorrect)