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AMC 12 2025a Problem 23

  • Paper

Call a positive integer fair if no digit is used more than once, it has no 00s, and no digit is adjacent to two greater digits. For example, 196,23,196, 23, and 1246312463 are fair, but 1546,3201546, 320 and 3432134321 are not. How many fair positive integers are there?

(A) 511(B) 2584(C) 9841(D) 17711(E) 19682\textbf{(A) } 511 \textbf{(B) } 2584 \textbf{(C) } 9841 \textbf{(D) } 17711 \textbf{(E) } 19682

Dataset text AMC 12 2000 to 2025. Quoted with source.

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C

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