Owlet puzzle #41
Released Saturday, August 15, 2026 UTC
1111
the answer for puzzle #41
The five clues
- A four-digit number, all identical digits.
- A repunit in base 10.
- Equal to 11 × 101.
- Not prime, but pleasingly symmetric.
- R₄ — the repunit written with four ones.
Backstory
1111 = 11 · 101 is the repunit R₄ = (10⁴ − 1)/9. Repunits R_n are prime only when n is prime, and even then rarely: R_2, R_19, R_23, R_317, and R_1031 are the only known repunit primes, so R_4 = 1111 is composite as expected.
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