Are there any single digit arithmetic facts, that still "stall" you as an adult?
That is despite your best efforts to "just memorize" you still need to think OK 8*7, that's like 8*8=64 less 8=4+4, so 64, 60, 56... or similar?
I really wonder about how the brain works, and WHY the way I remember 8*8 feels so different from 8*7? Is there any research into this kind of memory?
The former is instant, and free of doubt. The latter takes a few seconds. Why?