UKMT Pink Kangaroo, 2016

Number theory Difficulty 2.0 Junior Find the answer United Kingdom

Sepideh is making a magic multiplication square using the numbers 1, 2, 4, 5, 10, 20, 25, 50 and 100. The products of the numbers in each row, in each column and in the two diagonals should all be the same. In the figure you can see how she has started. Which number should Sepideh place in the cell with the question mark?

(A) $2$ (B) $4$ (C) $5$ (D) $10$ (E) $25$

Figure for this problem

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