The ultimate question of life, the universe, and everything is indeed asking what is 6 multiplied by 9. (42 of course, as any well-read high school student could tell us.)
It's unclear. It's proceeded by a discussion that the question may have been garbled. So we're left with two possibilities:
1) The ultimate question was 6 * 9 = ? and the universe makes no sense at all.
2) The ultimate question was 6 * 7 = ? and the universe has no deeper meaning.
Both are possible, and the ambiguity suggests he wanted to say both.
Have you ever read the source material? If not, you should, and if you have, you still should, since that was a quote