Leonardo Pisano, "Fibonacci"

Aug 01, 2020 306

BY: Marianna Randazzo

XXXV plus L equals LXXXV, 85. For more than 1,000 years, Romans did their math with these numerals, and school children across America were taught this fun way of writing numbers known as Roman Numerals. But, for the Romans, computing large sums as commerce increased and trade extended throughout the world, became cumbersome.

When Marco Polo brought the abacus from China, the tool was as innovative as today's smartphones. However, they still needed simple numerals, zero, algebra, and geometry to carry on worldwide trade. Leonardo of Pisa, who posthumously was given the name Fibonacci, is credited with introducing Europe to Arabic numerals, which in turn presented key algebraic concepts to Roman math.

Leonardo Pisano was born late in the twelfth century in Pisa. "Pisano" in Italian indicated that he was from Pisa, His father was a wealthy merchant called Guglielmo Bonaccio, and it's because of his father's name that Leonardo Pisano became known as Fibonacci. Centuries later, when scholars studied the handwritten copies of Liber Abaci,  they misinterpreted part of the title – "filius Bonacci," meaning "son of Bonaccio" – as his surname. Thus Fibonacci was born.

Fibonacci lived from about 1170 to 1240. Guglielmo took his son with him while he worked in Northern Africa. While there, he learned about negative numbers, zeroes, and fractions. From about 1200 on, Fibonacci dedicated himself to writing mathematical manuscripts to explain these vital mathematical concepts.

Fibonacci is remembered today for the equation he explained in his book through the use of rabbit reproduction. He posed a question: "How many pairs of rabbits can be bred from one pair in one year?" What became known as the Fibonacci number is the answer. The number of rabbits grows exponentially as each new rabbit produces more animals to add to the original pair: 1 +2=3; 2+3=5; 3+5+8, and so on the sequence goes.

Today the Fibonacci numbers are used by scientists to calculate population growth and stockbrokers to predict the market. Farmers and multitudes of others use it as well. The Fibonacci sequence is also found in nature, such as in the petals of flowers. Most flowers have three such as lilies, and irises, others have five, others have eight such as cosmea, daisies have thirteen. The Fibonacci sequence continues up to eighty-nine as in Asteraceae petals.

For those of you who enjoy literature and pop culture, you will find references to the Fibonacci sequence in the following stories and movies; The DaVinci Code (2006), PI (1998), 21 (2008), A Brilliant Young Mind (2015), and  A Wrinkle in Time (2018). These are just a few!

SOURCE: Garibaldi-Meucci Museum

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