Nonmathematical people sometimes ask me, You know math, huh? Tell me something I’ve always wondered, What is infinity divided by infinity?

I can only reply, The words you just uttered do not make sense. That was not a mathematical sentence. You spoke of infinity as if it were a number. It’s not. You may as well ask, What is truth divided by beauty? I have no clue.

I only know how to divide numbers. Infinity, truth, beauty — those are not numbers.

Then the person says, No, I mean, what is:
And I say, Oh.  Um, 3.

— John Derbyshire, in “Prime Obsession” (addendum by Alex Boisvert)