The specific reason would depend on the ones given by the organization or entity that banned it. In general, conservative Christian groups would want it banned because it makes light of God and the Creation story.
It never has been, as far as I know, other than that both the radio play, the TV series and the film all contain a few obscenities that some broadcasting companies might have refused to air.
Space
The Hitch-Hiker's Guide to the Galaxy is 100% fact in the 42nd dimension.
Shynola
Approximately 15% of schools list The Hitchhiker's Guide to the Galaxy in their curriculum.
hitchhikers guide to the galaxy... it's a hilarious movie
2
Because it says so in the hitchhikers guide to the galaxy.
for leaving just before the world exploded in the hitchhikers guide to the galaxy
The brilliant book does not tell you, that's the point of the book!
The concept of "the meaning of life is 42" comes from Douglas Adams' book "The Hitchhiker's Guide to the Galaxy," where 42 is the answer to the Ultimate Question of Life, the Universe, and Everything, calculated by a supercomputer over millions of years. It's meant to be a humorous and ironic take on the philosophical question of existence. So, you didn't miss anything concrete; it's more of a playful and satirical interpretation of the quest for meaning.
The "trilogy" of five books were published between 1979 and 1992.
Hit 4-2 in that order. It's from The Hitchhikers Guide to The Galaxy.