## Mathematical Monday 8-16-10

Time for another fun math fact on this mathematical Monday!

I’m good at math, but I’m crummy at memorization. Therefore, back in the day I used a number of tricks to do simple math. Here’s one of my favorites: nine times tables on you hands.

To do 9 x anything, you hold your hands out in front of you with fingers out. Then you count from left to right the number of anything and drop that finger. The answer is now in front of you! Count the fingers to the left of the one that’s bent, that number goes in the ten’s place. Count the fingers to the right, that number goes in the ones.

Here is a great video explaining it all to you!

Now you will never forget these, or at least you won’t need to memorize them!

1. aqeelk
Aug 16, 2010 @ 16:30:19

I have never understood how this works until now. However I know of another way, as you times something by an extra nine, the tens column increases by 1 and the units decreases by 1.

1 x 9 = 09
2 x 9 = 18
3 x 9 = 27
4 x 9 = 36
5 x 9 = 45

etc.

http://geekdome.wordpress.com

2. Jaclyn
Aug 18, 2010 @ 06:41:13

I remember learning this in grade school. it was an amazing trick that helped me free up valuable brain space for other, more useful things… like the names of all the ships in Star Wars or how many times Captain Kirk got the girl…

Aug 18, 2010 @ 20:46:35

Since I am disilyic, I had to use a different way to remember the multiplies of 9 for example I used a little subtraction I knew that 9 x y was equal to the difference of 10 x y minus y
example
10x 3= 30
30-3=27
thus 3×9 =27.
then there was the old fashion way which was drill the multiplication tables in my head.