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Celebrate Fibonacci Sequence Day — November 23: From Rabbits to Spirals

11:43 PM, 11/21/2025
Celebrate Fibonacci Sequence Day — November 23: From Rabbits to Spirals

November 23 is observed as Fibonacci Sequence Day, honoring Leonardo of Pisa (Fibonacci), who introduced the sequence in 1202 and promoted Hindu–Arabic numerals. The sequence begins 1, 1 and each term equals the sum of the two preceding terms (1+1=2, 2+1=3, 3+2=5). Its ratios approach the Golden Ratio and appear widely in nature and computing. Common celebrations include drawing Fibonacci spirals or baking spiral-topped pies.

Break out the calculators: November 23 is Fibonacci Sequence Day, a playful celebration of one of mathematics' most enduring patterns.

What is the Fibonacci Sequence?

The Fibonacci Sequence is a simple numerical pattern first recorded in Europe in Leonardo of Pisa's 1202 book Liber Abaci. The nickname Fibonacci comes from the Latin filius Bonacci, meaning "son of Bonacci." Fibonacci introduced the sequence while posing a rabbit-reproduction problem and helped popularize the Hindu–Arabic numeral system (0–9) across Europe.

1 + 1 = 2 2 + 1 = 3 3 + 2 = 5 5 + 3 = 8

Each term is the sum of the two preceding terms. Though elementary, the sequence connects to surprising phenomena: ratios of consecutive Fibonacci numbers approach the Golden Ratio, a proportion found in natural spirals such as seashells, sunflower seed arrangements and, on a grander scale, the spiral structure of some galaxies.

Beyond natural patterns, Fibonacci ideas appear in computing and algorithm design (for example, Fibonacci heaps and recursive algorithms), as well as in art, architecture and biology. The sequence provides an intuitive bridge between elementary arithmetic and deeper mathematical concepts.

How to celebrate

Observances are light and accessible: draw a Fibonacci spiral, explore phyllotaxis by arranging seeds or leaves, map the sequence onto a piece of art, or bake a pie with a spiral crust. These simple activities make the math visible and fun for learners of all ages.

For ideas and activity guides, consult classroom resources and holiday trackers such as National Day.

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