Roman numerals

Parker was reading Stuart Little to me tonight, and got tripped up by the roman numeral chapter numbers. So we paused to talk about roman numerals for a while, which I was surprised he didn't know. We looked at a few, and talked about the pattern, and he figured it out in time to predict what 11-14 should be.

Then I said, "An interesting thing about roman numerals is that there is no way to write zero."

Parker sat for a minute the way he does, where you don't know if he heard you. And then he said, "What about IIIIIV?"