42 is from The Hitchhiker’s Guide to the Galaxy by Douglas Adams. They built an enormous computer called Deep Thought that was the most powerful ever built to calculate the answer to the Ultimate Question of Life, the Universe and Everything. The computer, after 75 million years of processing, came up with 42. The confused crowd that gathered to hear the answer did not understand. Turns out, 42 is the correct answer, but what is the question?
So after that, they decide to build another computer, which is planet Earth, to figure out the question.
It was still calculating when it was destroyed by the Vogons to make space for a hyperspace bypass.













I’ve heard it said that 420 referred to the time 4:20 pm, when a group would come together to smoke, but that sounds contrived.
420 can also refer to the birth date of Adolf Hitler, which makes 420 a bit darker than just “haha, smoke.”