# A magic square

Logic Level 3

What is the minimum number of cells of a $$3 \times 3$$ grid that need to be filled so that you can fill the rest to obtain a unique $$3 \times 3$$ magic square?

Note: A $$3 \times 3$$ magic square is a grid filled with distinct integers from 1 to 9 such that the sum of the numbers in all rows, columns and diagonals is the same.

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