Actually, it's only ~32% more combinations to learn, because nobody really needs to memorize the 10's and 11's (except 11 x 11). You memorize all the combinati

Actually, it's only ~32% more combinations to learn, because nobody really needs to memorize the 10's and 11's (except 11 x 11). You memorize all the combinations up to 9 x 9, compute the 10's and 11's on the fly, and memorize the 12's. Edit: Corrected the number. This is how you get 32%: The 9 x 9 multiplication table contains 8 x 8 = 64 combinations to memorize. The 1's don't count. The 12 x 12 multiplication table contains an additional 20 combinations to memorize, namely: - 10 combinations from 12 x 2 to 12 x 12, not counting 12 x 10 - 9 combinations from 2 x 12 to 11 x 12, not counting 10 x 12 - 11 x 11 = 121 So the total is 84 combinations, which is ~32% more than 64.