Includes 5 easy puzzles, 30 mild puzzles, 5 'Alpha Doku' letter puzzles, 40 difficult puzzles, 20 fiendish puzzles. For those still in the dark, Su Doku is a number grid consisting of 9 large squares each divided into 9 smaller squares. You must complete the grid so that every column, every row and every 3x3 box contains the digits 1 to 9.