I was helping Colin get dressed this morning and I happened to be wearing an old tee shirt with the RSA algorithm on the front. Colin starts reading, "P, Q, P, R, I, M, E, N...I don't know that one, daddy, looks like a ladder (it was an "=" sign), P, Q...." He runs through it all and asks, "uh, what words are those?" I told him they're not exactly like the words he knows but they still mean things like words in a different language. Since he's been chugging along with addition fairly well recently I saw no reason to ruin his Sunday by explaining the difficulty in factoring very large numbers so I said that he could learn more about it in school someday, if he wanted to. Colin looked pensive for a second then sort of shrugged.
I suspect that art and recess just won a major rock-paper-scissors round over mathematics and cryptology.