Really I don't. I do "the old way" unless I happen to spot a nice pattern. (in this case the pattern involves knowing that 17 times 2 is 34 and that 17 times 3

Really I don't. I do "the old way" unless I happen to spot a nice pattern. (in this case the pattern involves knowing that 17 times 2 is 34 and that 17 times 3 is 51) My speed and reliability allowed me to focus on understanding higher-level math. With little effort, I easily blew past my peers for years afterward. Using pflat's method, my reliability would drop. There are too many extra numbers to account for.