Take a look at Grasshopper's post from the Story Page. Some pretty informative info about Mayan math, among other things. Could be relevant. Here's a snip, although the rest of the post is worth reading too:

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In a post I just read from Chelsea, there are several mentions of tic-tac-toe, as well as Mayan math. The book I'm reading shows how Mayans performed mathematical operations (+ - * /) by using a mat, or checkerboard, that was either three by three squares (i.e., nine squares total), or four by four (i.e., sixteen squares total.) It seems the 3x3 might be applicable, especially since it's often used in cryptograms as well.

There is a specific way to use these checkboards for mathematical purposes. I haven't figure it out yet, but maybe someone can.
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