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Fibonacci Numbers

1, 1, 2, 3, 5, 8, 13... — the sequence where every number is the sum of the two before it.

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Fibonacci Numbers — Key Facts

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Frequently Asked Questions

What are Fibonacci numbers?

The Fibonacci sequence is a series where each number is the sum of the two before it: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55...

What is the Fibonacci rule?

F(n) = F(n−1) + F(n−2), with F(1) = 1 and F(2) = 1.

Where do Fibonacci numbers appear in nature?

In sunflower seeds, pine cone spirals, flower petal counts, and nautilus shells — connected to the golden ratio φ ≈ 1.618.