I was sitting next to DD at a sporting event when she suddenly commented, "If a proper fraction has a prime number in the denumerator, it can't be simplified. Is that right?"

Me: "Huh? Um...yes, I guess that's true. Why are you thinking about that??"

DD: "I don't know. My brain just thinks about number things sometimes."

It's not such an world-changing "theorem," but the thing that gets me about this is the way she's prone to spouting these at the most random moments. My brain definitely does not work this way!