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UKMT Junior Kangaroo, 2022

Combinatorics Difficulty 2.0 Junior Find the answer United Kingdom

Joseph writes the numbers 1 to 12 in the circles so that the numbers in adjacent circles differ by either 1 or 2. Which pair of numbers does he write in adjacent circles?

(A) $3$ and $4$ (B) $5$ and $6$ (C) $6$ and $7$ (D) $8$ and $9$ (E) $8$ and $10$

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