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Did You Know, November 20, 2023

Thursday, November 23rd, is not only Thanksgiving, but also Fibonacci day. Leonardo Bonacci, born around 1170, was the son of an Italian customs official who directed a trading post in what is now Algeria. It was here that Fibonacci – short for filius Bonacci, or son of Bonacci – learned about the Arabic number system. As he traveled and conversed with various merchants, he realized the strength of this system over the use of Roman numerals because of the inclusion of place value. His book Liber Abaci, or The Book of Calculation, popularized the Arabic number system’s use in Europe by showing its value in bookkeeping. The time it saved actually led to growth in the European banking and accounting world.

Fibonacci explained the sequence that bears his name in discussing an exercise in estimation regarding rabbits reproducing in an enclosed space. Beginning with “1, 1” each subsequent number is the sum of the previous two numbers. Connected to the Fibonacci sequence is the Golden Ratio (1 to 1.6) and the Fibonacci Golden Spiral. These show up in nature in the design of pinecones, daisies, sunflowers, ferns, snail shells, sea shells, spiral galaxies, and some common fruits and vegetables.

The Fibonacci sequence, which was given that name in 1877 by French mathematician Edouard Lucas, has been applied to many aspects of our world:

· predicting the behavior of financial/stock markets

· architecture (ex. the Great Pyramid in Giza)

· art (ex. “The Great Wave” by Katsushika Hokusai)

· software design

· engineering

· estimating the effort, resources, and time involved in completing a given project

· preparing model virus breakouts

So, how can you celebrate Fibonacci day (which is celebrated on November 23rd because, when written out in numbers as 11/23, it forms the Fibonacci sequence 1,1,2,3)? Some ideas are:

· look for the Fibonacci sequence in works or art of create your own

· take a walk and search for it in your natural surroundings

· prepare a meal based on foods in which the sequence occurs

· check out Mensa for Kids’ series of “Fabulous Fibonacci” activities

Then, on the following Friday, Saturday, or Sunday, stop by the Dahlgren Heritage Museum between the hours of 10 am and 4 pm to see some research by Dr. Charles J. Cohen. This Dahlgren pioneer studied the Fibonacci sequence after retiring from his work on base.

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