Stephen Fry claims that Douglas Adams told him why he chose the number 42 as the answer to the “Ultimate Question of Life, the Universe, and Everything.”

In the first novel of Douglas Adams’ hit comic fiction series The Hitchhiker’s Guide to the Universe, a group of hyper-intelligent pan-dimensional beings demand the answer to the “Ultimate Question of Life, The Universe, and Everything” from a super computer by the name of Deep Thought. It takes Deep Thought 7.5 million years to calculate the answer, and that answer turns out to be 42. 

Through the course of the series, it was never clearly revealed what exactly the “Question” was, and why 42 was its answer. Now, there have been many speculations as to why Adams chose “42.” Some say that it’s because 42 is 101010 in binary code, other say it has to do with the fact that light refracts off water by 42 degrees to create a rainbow. Adams has said that he just chose a random number; “I sat at my desk, stared into the garden and thought, ’42 will do’.” 

However, not even Adams’ own testimony that 42 is a completely random number, is enough to convince people that it is. Stephen Fry, a friend of Adams, claims that Adams told him “exactly why 42,” and that the reason is “fascinating, extraordinary, and when you think hard about it, completely obvious.” However, Fry says that he had to vow to keep that reason a secret, and will take it with him to the grave. 

(Source)