For what it's worth, my DS8 is younger, but also very into discovering patterns. He noticed on his own looking at a multiplication table that there are two boxes diagonally adjacent to every perfect square that are one less than that number, which did make me think of this thread. I didn't have a pencil and paper to show him at bedtime, but I did want to work through multiplying out (x+1)(x-1) so he could see why. Maybe this weekend.