math trick

This guy came to parent teacher conferences and told me this math trick that I know I'll forget so I'm going to put it up here.

Multiplying 6's 7's 8's and 9's with your hands
Step 1. Pick the numbers you want to multiply
Your pinkies are 6's
your ring fingers are 7's
your middle fingers are 8's and
your index fingers are 9's
So if you want to multiply 6 x 8 you will use the left pinky for 6 and the right middle for 8, and then...

Step 2. Touch the fingers together that you want to multiply and get ready for some math!
Now that you are touching fingers, like in the example the pinky and the middle are touching, you divide your hands in half. All of the fingers from the bottom of your hand up and including the touching ones are going to be tens, so add them up together. The fingers above your touching ones are for multiplying. You are going to multiply the number of fingers you have above the touching ones one your right hand by the ones left over on your left hand.

So if we are touching our left pinky and our ring finger together for 6 x 8, we have 4 fingers from the bottom of each hand up to our touching ones. These make 40.

You then have 4 fingers on your left hand and 2 on your right hand above your touching pinky and middle. These will multiply so 4 x 2 = 8.

Then you add the two together 40 + 8 = 48