Unless you are a savant of sorts, being able to do 134 * 23 in your head requires all three. For example, you note that 134 * 23 is really 134 * (20 + 3), whic

Unless you are a savant of sorts, being able to do 134 * 23 in your head requires all three. For example, you note that 134 * 23 is really 134 * (20 + 3), which is just 2680 + (100 + 34) * 3 which leads to 2680 + 300 + 102 = 3082. And that is just one way of doing it. I do agree that arithmetic ability isn't all that great. But there is more logic and reasoning involved than you would think at first sight.