It's the first Monday in May, so merrily mull over this Monday Math Square as today's mentalfloss.com Brain Game challenge. Good luck! 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). 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... READ ON

Today's mentalfloss.com Brain Games challenge is a brand-new Monday Math Square. Good luck! 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). 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,... READ ON

Have at it with a brand-new Monday Math Square to jump-start this week's quintet of mentalfloss.com Brain Games. Good luck! 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). 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... READ ON

As has become the custom here at the mentalfloss.com Brain Game, we open the work week with a new Monday Math Square. Enjoy! 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). 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... READ ON

Today's mentalfloss.com Brain Game is a new Monday Math Square. This one might be a little tougher than usual, so we've spotted you one digit (the 2) to help get you started. 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). One digit is already provided for you. Place the remaining digits 1 through 9 in their correct spots so that the mathematical equations work both across and... READ ON

Start your week off right with a new Monday Math Square for today's mentalfloss.com Brain Game. 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... READ ON

Now that the second season of The Walking Dead is complete, you can focus on a new Monday Math Square for today's mentalfloss.com Brain Game. 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... READ ON

The mentalfloss.com Brain Game opens a new week with a Monday Math Square. I tried to include a few 11s to coincide with our 11-on-12 theme. 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... READ ON

To begin a new week, the mentalfloss.com Brain Game brings you a new Monday Math Square. Enjoy! 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... READ ON

As has become custom on Monday, today's mentalfloss.com Brain Game is a new Monday Math Square. NOTE: We're actively working on ways to make the Math Square (and other Brain Game puzzles) interactive so that you can solve them on-screen. We'll keep you posted on the results. Good luck with today's puzzle! 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... READ ON

Today's mentalfloss.com Brain Game is another new Monday Math Square. Enjoy! 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... READ ON

Monday Monday, so good to me... Enjoy a new Monday Math Square for today's mentalfloss.com Brain Game. 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... READ ON

Here's a new Monday Math Square for today's mentalfloss.com Brain Game. Enjoy! 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... READ ON

You'll find the rare "double divide" in the middle horizontal row of the Monday Math Square for today's mentalfloss.com Brain Game. 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... READ ON

About one in every 2 million lobsters is born with a rare genetic defect that turns it blue.