In 1192 Leonardo’s father was appointed director in a commercial company in Bugia (Algeria). In this city Fibonacci had an Arab teacher and learned to calculate with the new Indian-Arabic numerals that we use nowadays. Leonardo travelled to Egypt, Syria, Greece, Sicily and the south of France. In these places he met erudite and mathematics students.
In 1200 Fibonacci came back to Pisa, where he was born in 1175, and wrote several books with mathematical contents. We only keep: Liber Abaci (1202), Practica Geometricae (1220), Flos (1225), Letter to Theodor and Liber Quadratorum (1225).
In Liber Abaci, Leonardo da Pisa did a satisfactory processing in Arithmetic and Algebra. He shows how to name and write numbers in the Indian-Arabic system along the fifteen chapters of the book, explains calculating methods with natural numbers and fractions, calculates square and cube roots, obtains solutions of linear and quadratic equations, solves barter problems, etc… and investigates geometry in a practical sense. In this book the rabbit problem is proposed.
The solution of the problem drives you to the famous Fibonacci sequence: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144… where each number is the sum of the previous two.
It could be strange but we found the Fibonacci sequence in the spiral distribution of the leaves in a stem, in some groups of composed flowers, in a fountain designed by the North American mathematician and sculptor Helaman Ferguson, in a chimney in Turku (Finland), in two sculptures of the Australian Andrew Rogers placed in Jerusalem and in the Aravaca dessert (Israel)…