I learned my nines like that too, except I think the teacher showed us that trick. Of the things I learned personally… My tricks were more about avoiding the numbers I didn’t like than being efficient.
I could only ever remember how to add 8 to a number by adding ten and then subtracting two. I learned my 8 times tables by doubling the 4th multiple, and 7 by subtracting the base number from that. I suppose I only ever really memorized 2-6 and 12.
I learned my nines like that too, except I think the teacher showed us that trick. Of the things I learned personally… My tricks were more about avoiding the numbers I didn’t like than being efficient.
I could only ever remember how to add 8 to a number by adding ten and then subtracting two. I learned my 8 times tables by doubling the 4th multiple, and 7 by subtracting the base number from that. I suppose I only ever really memorized 2-6 and 12.