Favorite numbers

We were talking about favorite numbers, and Parker said his was 400. When I asked him why he said, "You know how I like music, and music comes on CDs, and also how I like Roman numerals better than regular numbers? Well, 400 in Roman numerals is CD."

Interestingly, I was reading old blog posts the other day and saw another instance where music and numbers collided weirdly in Parker's brain. See for yourself.