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UKMT Pink Kangaroo, 2017

Algebra Difficulty 2.0 Junior Find the answer United Kingdom

Maja decided to enter numbers into the cells of a $3\times3$ grid. She wanted to do this in such a way that the numbers in each of the four $2\times2$ grids that form part of the $3\times3$ grid have the same totals. She has already written numbers in three of the corner cells, as shown in the diagram. Which number does she need to write in the bottom right corner?

(A) $0$ (B) $1$ (C) $4$ (D) $5$ (E) impossible to determine

Figure for this problem

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