## Fibonacci Day is a chance to celebrate an interesting and ancient concept at the intersection of math, nature, technology, and art.

Math holidays like Pi Day and Pythagorean Theorem Day are a fun way to learn about new topics. You may have never heard of it before, but Fibonacci Day takes place annually on Nov. 23, the date of which was chosen because the first numbers of the Fibonacci Sequence are 1, 1, 2 and 3.

## What is the Fibonacci Sequence?

The holiday celebrates the legacy of Italian mathematician Leonardo Pisano Bogollo, better known as Fibonacci (Fibonacci was a nickname that roughly means “Son of Bonacci”). Fibonacci himself was born in Pisa, Italy, around 1170. He’s known for introducing Arabic numerals to the Western world and publishing a work that introduced the called Liber acaci that lead to the introduction of the Fibonacci sequence. The Fibonacci numbers have been characterized as “nature’s numbering system.” Fibonacci posed a conundrum during his lifetime that questioned what would happen if a certain man put a pair of rabbits in a place surrounded by a wall. The question asks how many new pairs of rabbits would be produced from that first pair in a year.

The resulting sequence begins with 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, a pattern of counting where each number is the sum of the previous two. This sequence appears commonly in nature in areas where growth can be measured. It’s found in seashells, plants and other living and nonliving areas. The sequence also is closely related to a number called the golden ratio and, in addition to being prevalent in nature, this type of system is used widely in computer data storage and processing. When we take any two successive Fibonacci Numbers, the resulting ratio is very close to the Golden Ratio, which is approximately 1.618034.

## Celebrating Fibonacci Day So how does one go about celebrating Fibonacci Day? One way is by learning about what the Fibonacci sequence means. Look in your home and the natural world around you to find examples of the sequence. You can also take the time to read about Fibonacci’s life and other mathematicians who have written about the Fibonacci sequence and the Golden Ratio. You might also bake Fibonacci spiral cookies. If you know someone crafty, maybe they could knit you this mathematically-inspired Fibonacci scarf. Share other ways to celebrate in the comments section!

Read on for information about other weird and cool STEM holidays like National Mole Day.

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