domingo, 5 de enero de 2014

THE WONDERFUL NINE TIMES TABLE

Though I am not so fond of maths, I am presently in the mood for a mathematical digression which, on account of its visual symbology, may prove useful to someone interested in the arts and literature.

As a child, which one of you readers did find it easy to remember the nine times table?
I was one of the large majority that didn't, until my first Maths teacher showed me a clever trick to remember it.
First, all one needs to do is write a vertical list of numbers from zero to nine:

0
1
 2 
3
4
5
6
7
8
9

Then, count down from nine to zero in a second list, next to the first one:

09
18
27
36
4  
5  
6  
7  
8  
9  

The result should be like this:

09
18
27
36
45
54
63
72
81
90

Ta-da!

The most striking feature of the nine times table is its chirality. In other words, its quality of being "obverse and reverse", like you and your mirror image, or like both your hands (which surely look like mirror images of each other). This chirality also makes the nine times table a palindrome: a sequence that reads the same both forwards and backwards (a literary example would be "ABLE WAS I ERE I SAW ELBA", or, for the most daring and observant, "A MAN A PLAN A CANAL PANAMA"):

 09 18 27 36 45 54 63 72 81 90

Another peculiarity of the nine times table is the fact that the digits of every number (to show a further peculiarity, all said numbers are multiples of 3) add up to nine: 0+9, 1+8, 2+7, 3+6, 4+5, and the commutative property of addition (the reason why 4+5 equals 5+4) will show that it's true about the rest.





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