Owlet puzzle #105
Released Sunday, October 18, 2026 UTC
45
the answer for puzzle #105
The five clues
- A two-digit triangular number.
- A two-digit Kaprekar number: its square splits into halves that sum to itself.
- Sum of the digits from 0 to 9.
- The interior angle of a right isoceles triangle's non-right angles (in degrees).
- T₉ = 45; also the atomic number of rhodium.
Backstory
45 = T₉ = 1+2+…+9 is the ninth triangular number, and a Kaprekar number: 45² = 2025 splits as 20+25 = 45. It's also the sum of a standard 3×3 magic square's cells and equals the number of unordered pairs from a 10-element set: C(10,2) = 45.
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