This morning a friend emails me this story about a "half a petaflop" supercomputer, adding the semi-obligatory joke "Let's calculate PI!"
"Old joke," I respond. "Have you heard about the new Cray supercomputer? It can calculate the sum of digits from 1 to infinity in 4.5 seconds."
A polite smiley followed.
"Wait," I responded to myself after a pause, "Isn't the sum of digits from 1 to infinity just infinity squared? Hell, that didn't take me 4.5 seconds either. I think I told the joke wrong."