As you enjoy the first full week of spring (out the window, at least), give the Monday Math Square a shot. Here's today's mentalfloss.com Brain Game:
Place the digits 1 through 9 in the white blanks so that the mathematical equations work both across and down. Each digit 1 through 9 should appear only once in the main grid (the red square).
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 your numbers with us in the comments).