Forty Two

Near the end of The Hitchhikers Guide to the Galaxy, Douglas Adams describes how a race of hyperintelligent pandimensional beings decided to build the greatest computer in the history of the universe to solve the question of Life, the Universe and Everything. They named their supercomputer Deep Thought, and despite its enormous processing power, it required seven and a half million years to determine the answer.

Generations later, on the Great and Hopefully Enlightening Day, the Day of the Answer, Deep Thought surprised the scientists, philosophers and religious leaders by revealing that the answer to the question of Life, the Universe and Everything was Forty Two.

If you want a useful answer, chose your questions carefully!