Question 55
Define *magic square* as a $3 \times 3$ table where each cell contains one number from $1$ to $9$ so that all these numbers are used and all row sums and column sums are equal. Prove that any two magic squares can be obtained from each other via the following transformations: interchanging two rows, interchanging two columns, rotating the square, reflecting the square w.r.t. its diagonal.