It's a cool story... Only that it's not true.

To quote Douglas Adams:
"The answer to this is very simple. It was a joke. It had to be a number, an ordinary, smallish number, and I chose that one. Binary representations, base thirteen, Tibetan monks are all complete nonsense. I sat at my desk, stared into the garden and thought '42 will do' I typed it out. End of story."

source:
https://groups.google.com/g/alt.fan.douglas-adams/c/595nPukE-Jo/m/koaAJ3tPBtEJ?pli=1