"42 is the number with which God creates the Universe in Kabalistic tradition"
But beware: The hit on the BBC (on which the radio version appeared) is
"BBC Online - Cult - Hitchhiker's - Guide - The Ultimate Answer"
And remember, all of this is on the Internet, so it must be true.
If Google says so, it must be true.
Go to Google and try searching:
the answer to life, the universe, and everything