Sums of Squares of Diagonals of Order 3 Magic Square

Theorem
Consider the order 3 magic square:

The sums of the squares of the diagonals, when expressed as $3$-digit decimal numbers, are equal to the sums of the squares of those same diagonals of that same order 3 magic square when reversed.

Proof
For the top-left to bottom-right diagonals:

For the bottom-left to top-right diagonals:

Also see

 * Sums of Squares of Lines of Order 3 Magic Square