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Fibonacci spiral

Compute the Fibonacci sequence — and discover the golden ratio.

Maker· ages 12–1425 minwhile loopslistsindexingdivision

fib.py

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First load pulls ~10 MB of Python. Only happens once — the browser caches it after.

What should the output look like?

You should see the sequence printed with bars, and a golden-ratio calculation at the end.

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How this works

Each Fibonacci number is the sum of the two before. Shows up everywhere in nature — flowers, seashells, pineapples. As the sequence grows, the ratio of consecutive numbers gets closer to the golden ratio (1.618).

Your turn — try these

1Compute the 100th Fibonacci number. How many digits does it have?
2Make it print only Fibonacci numbers that are also prime.
3Print the sequence "in reverse" — from the biggest back to 0.