Fibonacci Day

In dark times in medieval Europe, despite the enormous power of the church over people and the pressure of religious dogmas, science was actively developing. One of the brightest representatives of mathematics of that time was Leonardo Pisano. The scientist introduced Arabic numerals, the concept of zero and prime numbers, and introduced the decimal number system into use. Pisano was born in 1175 (or 1170) in Pisa in the family of the merchant Guglielmo dei Bonacci. It was no coincidence that Leonardo began to develop a practical guide to finding remainders, calculating the least common multiple and the greatest common divisor. This knowledge was necessary for trade developing in the Middle Ages. The mathematician signed his works “Leonardo of Pisa” or figlio Bonacci (“son of Bonacci”). His name is immortalized in history thanks to the discovered sequence of numbers in which each is equal to the sum of the previous two. The Fibonacci series is still used today in mathematical modeling and in predicting indices in stock trading. In addition, thanks to Pisano, the principles of the “golden ratio” and obtaining the “number of God” 1.618 became obvious. In honor of the great scientist, Fibonacci Day was established, celebrated annually on November 23. The date for Fibonacci Day was not chosen by chance. If you expand the Fibonacci numbers in a row, the first ones will be 1, 1, 2 and 3. According to Western tradition, when writing a date, the month is indicated first, and then the day and year. Therefore, Fibonacci Day is celebrated on November 23, that is, November 23. If you divide each member of the series by the previous one, you get a result that steadily tends to 1.6180339. In the Middle Ages this was called divine proportion, today - the golden ratio, a universal manifestation of symmetry and beauty in the relationship of part and whole. The number 1.618, denoted in algebra 21 by the letter Phi of the Greek alphabet, is present in the proportions of the human body, which is reflected in the drawing “Vitruvian Man” by Leonardo da Vinci. According to the laws of the golden ratio, a logarithmic spiral unfolds, on the principle of which the calcareous shells of the mollusks Nautilus pompilius and some species of snails, the Milky Way and other galaxies are built. The ratio of part to whole in the form of 1.618 is present in all areas of life - from biology to construction and painting. Thus, the proportions of the golden section can be found in “La Gioconda” and “The Last Supper” by da Vinci, in the Parthenon, a monument of ancient Greek architecture, in the Cathedral of Notre Dame de Paris, in the arrangement of petals in a flower and seeds in a sunflower. The Fibonacci sequence was established by Pisano by observing rabbits. Any pair of these animals produces offspring of two individuals every 30 days, starting from the second month of their existence. The Fibonacci series, where any number is the sum of the previous two, allows us to calculate that in a year the number of rabbits will reach 233 pairs. The funny and somewhat absurd premise of a serious scientific discovery does not in any way detract from the importance of the work of Leonardo of Pisa. Therefore, every year on November 23, Fibonacci Day is celebrated in many countries around the world.