Every Saturday a Dutch newspaper called NRC publishes a special Sudoku.
A normal Sudoku consists of 9 squares (3 by 3) but the NRC Sudoku has 13 squares which all must be filled with the digits 1 till 9. By using 13 squares they can create Sudoku’s with not more than eleven clues to start with.
To be able to solve Sudoku you need a NRC subscription. I know this is for most of the readers of Passion for Puzzles blog not an option. So if you want more information about the NRC Sudoku’s here is a link where you can a brief description of NRC Sudoku’s in English, including some Sudoku examples to solve. Happy Puzzling!