Nice Trick to Teach Your Kids--It'll Help Them With Their 9 Times Tables

This is really cool; watch this.

Hold your hands up, palms facing you, with your fingers outstretched. We're including the thumb as a finger in this scenario. What's 9 x 1? Hold down the thumb on your left hand, which is the first finger starting from the left, and how many fingers remain? 9. Try it again.

What's 9 x 2? Hold down the index finger on your left hand, which is the second finger from the left. How many fingers do you see? One finger to the left of your index finger and eight fingers to the right. 18. Try it again.

What's 9 x 3? Hold down the middle finger on your left hand, which is the third finger from the left. How many fingers do you see? Two fingers to the left of your middle finger and seven fingers to the right. 27. Try it again, and again, again, one at a time until you reach 9 x 9.

What's 9 x 9? Hold down the index finger on your right hand, which is the ninth finger from the left. How many fingers do you see? Eight fingers to the left of you index finger and one finger to the right. 81. It works for each multiplication of nine for as many fingers as you have to show.

There's nothing mystical about this and it doesn't actually teach your kids what they need to know about how numbers work, but it is a quick and easy shortcut, besides being a fun trick. It only works this way because our number system is based on units of ten--which of course is an arbitrary linguistic designation, but organizes our entire mathematical system.

My brother and sister-in-law at Georgia Tech can straighten me out about the details where I'm wrong.