

Finger Math: 9X Rule, Using hands: 1–10 multiplied by 9 - mquaes
http://mathema-tricks.blogspot.com/2011/12/finger-math-9x-rule.html

======
drostie
I must question your choice of audience. Granted, many startup founders need
to spend more time with their children, but teaching them to do multiplication
by 9 on their hands is a little dreary when compared to, I don't know, reading
them a story, building something with Lego bricks, or showing them how to
disassemble flash so that they can cheat at that online game they were
playing.

