1123 — the first numbers in the Fibonacci sequence — allows us to celebrate November 23rd as Fibonacci Day. This is in honour of Italian Leonardo Bonacci of Pisa who discussed the sequence in 1202.
The Fibonacci sequence goes as follows: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144 and on to infinity. Each number is the sum of the previous two. They were known in India well before Fibonacci and were called Virahanka numbers.
It might seem just like a simple mathematician’s trick, but the Fibonacci sequence is found throughout nature. For example, the petals on flowers follow the sequence — most flowers have three (like lilies and irises), five (parnassia, rose hips) or eight (cosmea), 13 (some daisies), 21 (chicory), 34, 55 or 89 (asteraceae). Spirals, such as in pine cones or conch shells, are also built up in Fibonacci sequences.
One could spend an entire Fibonacci Day finding more examples, from spiral galaxies to DNA sequences to fractal diagrams.