The numbers sum up to 45, so each row, column and diagonal must add up to 15, forcing number 5 (the average) in the center.
2 7 6
9 5 1
4 3 8
is a possible solution. Call it A.

Rotation about the diagonal 258 yields another solution:
2 9 4 7 5 3 6 1 8 Call it B.

Rotating each of the solutions 90 degrees 3 times , moving number 2 to 3 distinct corners, adds 3 more solutions for A & B each. Rotation about the diagonal 456 creates no new answers.

So there are 8 distinct solutions:- 2 & 8 at the ends of one diagonal, 4 & 6 the other, -all even numbers
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