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Sunday, December 15, 2013

Who was this Fibonacci guy anyway?

Leonard Pisano (1170-1250),
also known as Fibonacci.
Photo credit:

You may already know of a famous Italian named Leonardo. He was an artist, inventor, mathematician, scientist, and more. Leonardo was from a town called Vinci in the Tuscany region. For that reason, we commonly know him as Leonardo da Vinci, or Leonardo from Vinci.

However, you may not know about the other famous Leonardo, who was also from Tuscany. You see, he was born and, later in life, lived in Pisa (the town with that leaning tower). So he was originally known as Leonardo Pisano (as in 'Leonardo, the guy from Pisa'). He also went by the name Leonardo Bigollo (wanderer, good-for-nothing).

But you see, as a child, Leonardo was not as well known as his father, Guglielmo Bonacci. Bonacci was a diplomat who represented Pisa in business dealings in North Africa. Leonardo was trained in accounting by African teachers, and didn't return to Pisa until he was around 30 years of age.

In Italian, the word 'figlio' (FEEL-yo) means 'son'. So Leonardo, who was the son of Bonacci, was known as "Figlio di Bonacci", the son of Bonacci. Over time, it shortened down to Fibonacci.

Fibonacci's most famous work was the Liber Abaci, or The Book of Calculation. In that book, he posed the following question:

A certain man put a pair of rabbits in a place surrounded on all sides by a wall. How many pairs of rabbits can be produced from that pair in a year if it is supposed that every month each pair begets a new pair which from the second month on becomes productive?

One can see that this problem elicits the sequence 1, 1, 2, 3, 5, 8 ,13, 21, 34, .... 

The Fibonacci Sequence as seen in a
growing rabbit population.
Photo Credit:

I doubt old Leonardo could have predicted just how many places his numbers would turn up over the next 800 years. Over the next several posts, I will be exploring the unusual, the unexpected, and the truly unbelievable places you might run into a Fibonacci number. We will be looking at the fields of botany, zoology, marine biology, design, architecture, and even the stock market.

Stay tuned.

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