Earlier quoted context omitted.
Can't understand modern world without understanding statistic, can't do that without algebra and basic calculus, can't do that without being at least adequate at mental multiplication (for calculating parameters in equations and understanding how they change without interrupting your train of thought every 3 seconds). So yeah, I think you still need to grind these multiplication tables, even if you have perfect versi…
Have you noticed that most adults don't know what nine times seven is? If you ask them on the street they'll mostly either get it wrong or tell you quite rudely to go away. This is despite (and because of) a decade of grind at school. Or have you noticed that people are unable to hold a conversation in a foreign language despite years of 'study' in a classroom? Whereas an enthusiastic individual can pick up basic con…
But I can kinda understand why, you almost never have to multiply 9*7 by hand. If you're doing algebra or any symbolic calculations you rarely use digits other than 0-4.
In real world Benford's law + usual rounding greatly reduces the need to multiply by 7 or 9 (or 8 for that matter).