Editors -- perhaps save this for the weekend?
Mathematician John Baez presents a delightful and beautifully illustrated version of the ultimate question...
http://www.math.ucr.edu/home/baez/42.html [ucr.edu]
for which the answer is 42.
Hint -- it's 2D geometry. And maybe the mice should have been bargaining with Zaphod for his brain instead of for Arthur Dent's brain.
Lots more math & physics fun on his pages, I also enjoyed http://math.ucr.edu/home/baez/rolling/ [ucr.edu]