Friday, February 15, 2008

Remember This?

I was reading 10 Easy Arithmetic Tips. I had forgotten all about this:
Multiplying by 9

To multiply any number between 1 and 9 by 9, hold both hands in front of your face, with fingers extended. Now drop the finger that corresponds to the number you are multiplying (for example, for 9 x 3, drop your third finger). Now count the fingers before the dropped finger (in the case of 9 x 3 it is 2) -- that's your first digit. Then, count the fingers after (again in this case, it’s 7). The answer is 27.
Back when my kids were in elementary school, I used to go in and help with 'Math Facts' which involved flash cards, addition, subtraction, multiplication, and helping the kids with all manner of math related things. This was one of the tricks we used. There are some other tricks there that I didn't know about. You never know when I might need to do some math.


  1. Also you can do a countdown run, by writing your numbers up and then down 0,1,2,3,4,5,6,7,8,9 and then backwards run 9,8,7,6,5,4,3,2,1,0 putting those number together you have your 9's, for example, 9x0 equals 0, 9x1 equals 9, then 9x2 equals 18, 9x3 equals 27 and so on...I like your way a lot better, because you don't have to write it down, like this method.

  2. I had never heard this trick before!!! That's pretty neat!

  3. This is a fun tip. My son learned it at school (3rd grade) and then tried it with some other numbers, and was disappointed when it didn't work. Wish I had known this back in elementary school! :-)

  4. I remember my older brother teaching me this trick when I was little and I thought it was so weird that they didn't teach it to me in school. I have been using the touchpoints to teach adding to my son...I am wondering if they will use it in school or not.


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