It isn't necessary, nor particularly useful. Once you know the multiplication tables for one-digit numbers, you can do multiplication on paper for larger numbers. The time spent to memorize such multiplication tables for larger numbers would be better spent learning more advanced math concepts.
Of course not.
No, it is not.
The bullet represents a multiplication. You are supposed to do the multiplication before you do the additions.
None, because there is no multiplication involved.
6x5
Four plus four plus three?
plus saka minus
511 x 5
42
-9
-/+ = - +/- = - +/+ = + -/- = + Same goes for multiplication.
Multiplication and addition.