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UKMT Grey Kangaroo, 2024

Combinatorics Difficulty 3.0 AMC 10/12 Find the answer United Kingdom

Werner can make a $4 \times 4$ square, where the sums of the numbers in all four rows and in all four columns are the same, from the three pieces shown and one further piece. Which of the following pieces is needed to complete his square?

(A) $1\ 1\ 3$ (B) $2\ 1\ 0$ (C) $1\ 2\ 1$ (D) $2\ 2\ 2$ (E) $2\ 2\ 3$

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