1. Sudoku is not a Chinese or Japanese puzzle. It was first published in its current form in the United States.
2. Sudoku became a hit in 2005 and was recognized as the fastest growing puzzle game in popularity. Only Rubik's cube can compare with it.
3. Sudoku can only have one single solution. The advantages of several solutions are the "fairy tale" of the owners of a low-quality Sudoku generator.
4. Sudoku solutions should be found logically, not by brute force or guessing.
5. Sudoku is a semantically independent puzzle, ie. not tied to the alphabet, therefore it is available for a person of any nationality. Any nine different characters can be used instead of numbers.
6. Sudoku online does not require special knowledge or vocabulary, to solve this puzzle it is enough to be able to think logically and visually distinguish nine different symbols. Therefore, this puzzle is available for people of different ages and educational levels.
7. According to Bertham Felgenhauer's calculations, Sudoku has 6 670 903 752 021 072 936 960 different combinations.
8. The first world Sudoku championship was held in Italy in the city of Luca in 2006. The first winner was Yana Tilova from the Czech Republic.
9. Free web Sudoku develops memory, logical thinking, helps with concentration and fights dementia. Useful at any age to develop mental abilities and keep them in excellent condition. Psychologists say that Sudoku can cure depression.