Page 244 - Mind Games The Aging Brain and How to Keep it Healthy

228 • Chapter 7

You found another pattern. The sum is always 9. Here is
the fun part. Because the numbers always add up to 9, you
only need nine fingers to represent the numbers in the table.
You can use your hands to multiply by 9. Consider the dia-
gram in Figure 7-2. Place your hands on the table in the
same manner.

3 8
2 4 7 9
1 10
5 6

Figure 7-2 Number assigned to digits

Suppose you want to show 4 x 9. Tuck the finger num-
bered 4, the index finger of your left hand, under your hand.
This may be difficult at first if you have arthritis in your
hands, but the exercise may improve your flexibility! There
are 3 fingers up on the left of finger #4, and there are 6 to the
right. 3, 6: The answer to 4 x 9 is 36. See Figure 7-3.

3 fingers 6 fingers

4

Figure 7-3 4 times 9 is 36