Sudoku quarterly, Fourth quarter 2021

A sudoku is a puzzle consisting of a 9 × 9 table in which a few of the digits 1,2,3,4,5,6,7,8 and 9 appear. They are sometimes called hints. The table is devided in nine 3 × 3 squares, called blocks.

To solve a sudoku puzzle, the blank cells have to be filled in. A proper sudoku is designed in such a way that it has only one unique solution. The solution to a sudoku is a special type of magic square: On each row and in each column the entries add to the same number. In the sudoku case this number is 45.

Since only the digits 1 to 9 may be used, in the solution all nine digits appear on each row and in each column. On top of this, each of the nine blocks should also contain these nine digits.


Since mid-2017 we only offer Magic Sudokus. This type of the puzzle contains one or more gray blocks.

In the solution, these gray blocks should also be magic: Each row and each column should add to 15 and all nine digits should occur.
For each week, the Sudoku on Monday has one magic block, the Sudoku on Tuesday has two magic blocks and so on. On Sunday all blocks are magic.

The Sudokus are generated using computer programs written in the language of the statistical package R. The results are written to LaTeX files which can readily be printed. The whole system was developed by Herman Adèr.

Over time, the system has been refined. Apart from the regular Sudoku’s (Sudoku’s without magic blocks), the program can also be used to generate so-called Ritmeester Sudoku’s, named after Peter Ritmeester, who proposed this type.

Presently, only magic Sudoku’s are given with an increasing number of magic blocks (1, 2, 3, 4, 5, 6 and 9).

To make the solutions even more interesting, we have developed a new algorithm to generate magic blocks. Sudoku Quarterly contains only Sudoku’s that are generated in this way.

To get a taste, download Sudoku weekly of week 51 (2021).




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March 28, 2022