I was doing a puzzle a few weeks ago when Mordechai (almost 7) asked me if 15 times 20 is 300. I was totally shocked and then he explained how he knew that. He had counted the pieces along the width and length of the puzzle and realized that by multiplying those numbers he would get the amount of pieces in the puzzle. Then he just had to look at the puzzle box for the answer!
(His math homework tonight was simple word problems requiring subtraction or addition with single-digit numbers. Something tells me he's not exactly being challenged in math class.)