First aired on BBC Radio 4 in 1978, The Hitchhiker’s Guide to the Galaxy is one of the most popular comedy series in the world. The science fiction cult classic has been adapted into books, comics, stage shows, a TV series, a computer game, and a feature film. Created by Douglas Adams, ecounts the adventures of Englishman Arthur Dent and his alien friend Ford Perfect. Though there are a lot of other interesting characters in the Galaxy, not many of them has befuddled fans like Deep Thought, a super computer.

As big as a small city, Deep Thought is the second greatest computer ever created. It’s activated by programmers Lunkwill and Fook, who belonged to a race of hyper-intelligent beings that looked like white mice. Its entire reason for existing was to compute a single answer to “Life, the Universe and Everything.” Although some people tried to influence and interfere with the process, Deep Thought produced an answer after seven and a half million years. It presented this answer to the descendants of the original programmers, Loonquawl and Phouchg. The answer was the number 42.

Immediately, the two perplexed programmers asked the computer to identify the Ultimate Question. In response, Deep Thought reproached Loonquawl and Phouchg, questioning if they knew the Ultimate Question. Acknowledging that it didn’t know the Ultimate Question, Deep Thought offered to create a superior computer to work it out. That computer was so huge that organic life became part of its original matrix and a supercomputer was born: the planet Earth. It would only take 10 million years to complete the calculations. Unfortunately, Earth was destroyed by the Vogons five minutes before the Ultimate Question could be calculated.

This is where story of The Hithchiker’s Guide to the Galaxybegins. Arthur and Ford are saved by Zaphod Beeblebrox just before Earth is destroyed. Later, Arthur learns that Earth is a supercomputer. The two descendants of Deep Thought’s original programmers realize that Arthur - a last-generation living byproduct of the computer’s matrix - has the Ultimate Question imprinted on his brain. When Arthur refuses to sell his brain to them, they attempt to steal his brain. They are stopped and the book ends with the group having lunch.

The number 42 plays a large role in the story. There is a theory that says if anyone is to discover the Ultimate Answer to the Ultimate Question (“Life, the Universe and Everything”), the universe will immediately disappear and be replaced with something that’s even more difficult to figure out.

Many fans theorize about why Adams chose the number 42. Some fans point out that 6 ₁₃ × 9 ₁₃ = 42 ₁₃ . In response, Adams replied that he would never make a joke about the number 13. Another theory points out that the total number of dots on a pair of dice is 42. Yet, a more puzzling idea says that if a person drills a hole through the Earth by its diameter, it will take 42 minutes for the person to be moved (by gravity) from one side to the other. The number also appears in many computer processes like data recovery. Despite all the theories, Adams had asserted that he chose the number randomly.