@Oylok,
Thanks!
We've been using a slightly different form of "lattice" math (one we found on the Khan website) and it really seems to help him keep the numbers organized.
More importantly, it's been interesting for him to see that there is more than one way to arrive at an answer -- it's kind of changed his way of thinking about math.
I was looking at some text sites yesterday about vedic math but they left me a little confused. I'm going to check out your video link!