Sudoku puzzles not only bring pleasure but also exercise concentration and attention. If you play daily, you will notice how quickly your ability to concentrate is improving.
The goal of Sudoku is to fill cells with digits from 1 to 9. The digits are located in 9 3х3 squares so that there are 9 cells in each line and each column. The same digit can be used only once in each particular column, each line and each small square.