Try using his love of math to develop other areas such as dot to dots for writing practise and mazes too. We gave dd an abacus to play with and that led to a lot of fun for her. Also I read that kids do better in advanced math later if they can Learn calculations in math stories instead of just numbers ( if a farmer has 3 core etc) apparantly it helps develop the visualisation required for higher math rather than rote learning. Good luck with your boy!