Today's mentalfloss.com Brain Game offers you Math Square #81. Good luck!
The nine white squares inside the main red grid should be filled with the digits 1 through 9. Each digit should appear only once in this main grid (the red square). Place the digits 1 through 9 in their correct spots so that the mathematical equations work both across and down.
Here is the SOLUTION.
NOTE: These puzzles rarely (but occasionally) have alternate solutions that fit the rules. If you find one of these, first make sure that you've followed the instructions to the letter, then pat yourself on the back (and feel free to share it with us in the comments).