Challenge your logic with a combination of math puzzles and classic sudoku puzzles free online. Place the numbers in the grid, so that none repeats within a row or column. The board is divided into segments, each presenting a problem. 40x means that the digits multiplied equal to 40 (e.g. 5x4x2). 3- means that the difference equals to 3 (e.g. 7 and 4). Play daily sudoku puzzles free online or do the printouts.