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Daily puzzle · 2026-10-22 · Combinations

Mathbound Daily Puzzle — 2026-10-22 — Combinations Solution

Level 3

Positive integer solutions to x1+⋯+x6=13x_1+\cdots+x_{6}=13 with each xi≤8x_i\le 8?
  1. A.795
  2. B.793
  3. C.787
  4. D.8568
  5. E.792

Answer: E

Key idea: Inclusion-exclusion after yi=xi−1y_i=x_i-1.

Set it up: Upper bound 8.

Solution: 792792.

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Mathbound Daily Puzzle — 2026-10-22 — Combinations Solution