math trivia

Finger MathMultiplying by 9
Hold out your hands in front of you so that your thumbs point toward one another.
Visualize that your left pinky finger represents 1, the next finger 2, and so on left to right, until your right pinky finger represents 10. Those fingers represent the number you wish to multiply by 9. To do so, simply put the finger down you wish to multiply by 9. All fingers to the left of the down finger represent the tens digit of the answer while all fingers to the right represent the ones digit.
Example: 6 x 9. Put the finger representing 6 down (the right hand thumb). To the left of the down finger, you have 5 fingers up. That's your tens digit. 5. To the right, you have 4 fingers up. There's your ones digit. 4. Put those together and you have your answer: 54.

http://library.thinkquest.org/J0110961/tnt.htm