by PaulIQ164 » Tue Feb 28, 2006 8:53 pm
I think it also helps a bit that there's an obvious order to go through the numbers in, so when you're counting off what's already in a row, you can go through them 1, 2, 3... . The same applies to letters (though it would be less easy if the leters were, say, CFGKLOSUZ instead of ABCDEFGHI), but with nine abstract symbols, you probably will have to make and remember an arbitraty ordering for yourself.