Multiplying On Your Fingers

My grandson showed me one way and this video showed me another way. My mind is blown.

https://www.youtube.com/watch?v=D7cZlzsmf5Y

 

used to do that, but 9s are different..

 

My mathematics are not very good. =\

 

That's neat. I never learned that in school. It works though.

 

Nines work with the video, Orison!

 

nine easier with palms down. whatever # digit you want to X by nine, fold it. count across left to right.. left hand 2nd digit down.. so u have one digit/ an 8 left. 18 .. middle finger left hand down 2 and 7. 27 ,,index left hand finger down 3 and 6.. 36 and so on. right hand thumb 5 and 4. 54 . try it..

 

The video - Both number 9 digits touching, they and every thing below them counts as 10 = 80, the fingers above multiply 1 x1 = 1 Add top fingers to bottom fingers 80 +1

 

Cool! I'll have to remember that trick for when/if I have kids.