100 different Sudoku puzzles in different degrees of difficulty and sizes from 4x4 to 16x16. The puzzles may be freely distributed or used for publication. The rules for solving a Sudoku are simple: Each row, column and region must contain the numerals from 1 through 9 exactly once. The Puzzles are in Adobe PDF file format and have not to be installed. You can easily print and then work them out with pencil and paper.