Owlet puzzle #101
Released Wednesday, October 14, 2026 UTC
5
the answer for puzzle #101
The five clues
- A one-digit prime.
- A one-digit prime that is also a Fibonacci number.
- It is the number of Platonic solids.
- A Fibonacci number, and also a Catalan number.
- The number of fingers on a typical human hand.
Backstory
5 is simultaneously prime, Fibonacci (F₅), and Catalan (C₃) — the smallest number that is all three. It's the only prime that ends in 5, the number of Platonic solids, and the smallest prime ≡ 1 (mod 4), so by Fermat's two-square theorem it's the smallest odd prime expressible as a sum of two nonzero squares: 5 = 2² + 1². (The even prime 2 = 1² + 1² also is, but trivially.)
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