Just smiling at your comment on your DS' 4's and 9's.

Our son also got marked off for those numbers.

Look at how they are here in this post! Our DS did them just like they are shown here.

His nines drove his third grade math teacher (when he was a first grader) nuts. She kept drawing over his upside-down six style nine with the old "ball and bat" style.

DS finally caught on that this is the price of admission.