My Lazy Way

          There was a sub in the eighth grade math class yesterday.  The instructor had left the instructions for the students to write out their 9 times tables from 1 – 25.  They were required to do in their heads and not use a calculator.  It’s not so bad doing in order.  1X9 of course is 9.  Just add 9 to it for your next answer 18 + 9 for your next answer: 27 and down the line.  Or you could use my lazy method which I have been doing since third or 4^th grade (whenever it was that we were taught)

          I never did memorize my 9 times tables, but tens were easy.  All you had to do was tack a zero to the end of the number being multiplied and then take that number away.  Thus 70 -7 is the same as 9X7.  I find subtracting a number is easier than trying to multiply:

          When I was taking courses on line, we required to look up references to back up our theories or understanding or whatever you want to call it.  I am sure that there are several others that may have come up with this same type of math solution for multiplying 9.  But we didn’t have the technology then when I figured out subtracting rather than memorizes the nines table.  Thus I am not going to provide any references other than the pictures I scanned of problems printed by my hand.  I’ve been doing it that way for decades.  It is what works for me.  There’s your reference.