Crossdoku addition is a great math crossword Sudoku puzzle to practice logic, math and deductive reasoning skills at the same time for the whole family adults and kids. It has many different Sudoku number junctions puzzles. It is a challenging math cross puzzle to improve memory, concentration and logical thinking skills. How to play: - Fill in the empty circles (octagons) so that the number between the four adjacent circles is the result of their sum. - But be careful a number can't be used more than once in any column or row like in Sudoku. - To fill the empty circle: drag the number to it or touch that circle. - To clear the non-empty circle: touch it again. The game has 7 different board sizes: 3X3, 4X4, 5X5, 6X6, 7X7, 8X8 and 9X9. Each size has many different puzzles. You have 60 minutes to solve each puzzle. You can manually or automatically save your progress to resume it later. Enjoy all fun and brain training with this math logic puzzle.