I misspoke... the actual thing was the answer to "Life, the Universe, and Everything". Turns out that yes, the answer is... 42.
It would appear that the question was the problem. The Earth was actually designed not to find the answer, but to find the question. Turns out, unfortunately, that the question for Life, the Universe and Everything, was: "What is six times nine".
But that's when it was destroyed.
Complete text of the section of the Hitchhiker's Guide on the Earth: "Mostly harmless".
Makes sense to me.