Today is Fibonacci Day

Every November 23rd, Fibonacci Day honors Leonardo Bonacci, one of the most influential mathematicians of the Middle Ages.  The date corresponds to the first numbers of the Fibonacci sequence, which are:  1 1 2 3.  Let me show you:

The Fibonacci Sequence is the series of numbers:

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ...

The next number is found by adding up the two numbers before it:

the 2 is found by adding the two numbers before it (1+1),

the 3 is found by adding the two numbers before it (1+2),

the 5 is (2+3), and so on.

That means the next number in the sequence above is 21+34 = 55.

Use those numbers to make squares, and we can make a spiral, like this one.  Aristotle called it the Golden Mean.  So the Fibonacci spiral and the Golden Mean are closely related.  Do you see now how Sandra Boynton drew her cartoon and why she called it the Golden Meanie?  To show the "meanness," she added those feet, horns, eyes, and clenched mouth with one sharp tooth showing.