1. Sudoku (数独 sūdoku?), also known as Number Place or Nanpure, is a logic-based placement puzzle. The objective is to fill the grid so that every column, every row and every 3×3 box contains the digits 1 to 9. The puzzle setter provides a partially completed grid so that there is only one solution.
Completed Sudoku puzzles are a type of Latin square, with an additional constraint on the contents of individual regions. Leonhard Euler is sometimes cited as the source of the puzzle, based on his work with Latin squares[1].
The modern puzzle was invented by an American, Howard Garns, in 1979 and published by Dell Magazines under the name "Number Place"[2]. It became popular in Japan in 1986, when it was published by Nikoli and given the name Sudoku. The name "Sudoku" is the Japanese abbreviation of a longer phrase, "Sūji wa dokushin ni kagiru" (数字は独身に限る "Sūji wa dokushin ni kagiru"?), meaning "the digits must occur only once" . It became an international hit in from Wikipedia
by D. Fisher

2. 4 3 1 4 3 4 1 2 Easy 4 by 4 puzzle A. For answers click once.
Sudoku techniques
Sudoku solving technique #1
Sole Candidate
When all the other possibilities for the sudoku cell have been removed, and only one choice remains - then it must be the correct value. Sudoku solving technique #2
Unique Candidate
If a cell is the only one in the row that can contain a certain number, then it must have that number. This is because every row of the sudoku must have each of the values 1-9. The same applies to columns and 3x3 blocks in the sudoku. Sudoku solving technique #3
Col/Row/Block interactions
If you know that a number must occur in a certain row, then you can eliminate that number as a possibilty for other blocks in the same row. Eg, if you know that the number 4 must appear in the 1st row of block 1 (2nd and 3rd rows being full) then you know that the number 4 cannot occur in block 2 or 3 in the sudoku. This applies to columns as well. Sudoku solving technique #4
Naked subset
if 2 squares in the same col/row/block have the same 2 candidates, then you can remove those numbers as candidates in the same col/row/block. This rule extends to cover 3 squares with the same 3 candidates, 4 etc. 2
For answers click once.

3. Easy 4 by 4 puzzle 4 3 1 2 A. 2 1 3 4 3 2 4 1 1 4 2 3

4. Easy 4 by 4 puzzle 4 1 B. 3 1 1 3 4 1
For answers click once.

5. Easy 4 by 4 puzzle 3 4 2 1 B. 2 1 4 3 1 3 2 4 2 4 1 3

6. Easy 4 by 4 puzzle 4 2 3 C. 3 4 3 4 4 2
For answers click once.

7. Easy 4 by 4 puzzle 4 1 2 3 C. 2 3 1 4 3 2 4 1 1 4 3 2

8. Easy 4 by 4 puzzle 3 1 4 D. 2 1 4 4 3
For answers click once.

9. Easy 4 by 4 puzzle 3 1 4 2 D. 4 2 3 1 2 3 1 4 1 4 2 3

10. 4 by 4 puzzle 3 4 2 E. 3 1 3 2 1
For answers click once.

11. 4 by 4 puzzle 1 3 4 2 E. 2 4 3 1 4 1 2 3 3 2 1 4

12. 4 by 4 puzzle 2 4 1 F. 4 4 1 2 3
For answers click once.

13. 4 by 4 puzzle 2 3 4 1 F. 4 1 3 2 3 2 1 4 1 4 2 3

14. 4 by 4 puzzle 3 1 G. 4 1 1 4 1 3
For answers click once.

15. 4 by 4 puzzle 3 1 4 2 G. 4 2 3 1 1 3 2 4 2 4 1 3

16. 4 by 4 puzzle 1 4 2 H. 1 4 2 3 4
For answers click once.

17. 4 by 4 puzzle 1 4 2 3 H. 3 2 4 1 4 1 3 2 2 3 1 4

18. Easy 6 by 6 puzzle 2 4 I. 3 5 2 6 4 5 3 4 2 1 1 2 4 5 5 6
For answers click once.

19. Easy 6 by 6 puzzle 6 2 4 3 1 5 I. 1 3 5 2 4 6 6 2 4 5 1 3 5 4 3 6 2 1 2 6 1 3 4 5 3 1 2 5 6 4

20. Easy 6 by 6 puzzle 3 2 5 6 J. 4 1 6 3 4 2 4 5 1 3 5 1 4 2
For answers click once.

21. Easy 6 by 6 puzzle 3 2 1 4 5 6 J. 6 4 5 2 1 3 1 5 6 3 2 4 2 3 4 5 6 1 4 6 2 1 3 5 5 1 3 6 4 2

22. 6 by 6 puzzle 5 2 1 3 K. 1 6 3 4 2 4 1 5 6 3 5 2 4 6
For answers click once.

23. 6 by 6 puzzle 6 4 5 2 1 3 K. 1 5 6 3 4 2 2 3 1 4 6 5 3 6 2 1 5 4 4 1 5 2 6 3 5 2 4 6 3 1

24. Hard 6 by 6 puzzle 5 6 L. 6 3 5 3 3 2 5 4 1 5
For answers click once.

25. Hard 6 by 6 puzzle 1 5 6 2 3 4 L. 4 6 1 3 2 5 2 4 5 1 6 3 5 4 6 3 1 2 2 3 5 6 4 1 6 4 3 1 5 2

26. Hard 6 by 6 puzzle 5 1 2 M. 6 2 4 6 5 2 3 1 2
For answers click once.

27. Hard 6 by 6 puzzle 3 4 5 1 2 6 M. 3 6 5 2 4 1 1 2 3 6 4 5 2 6 4 3 5 1 4 1 6 5 3 2 5 3 1 2 6 4

28. 9 6 2 7 4 3 8 6 N. 8 1 9 2 1 5 8 3 4 9 7
9 by 9 puzzle 9 9 8 6 5 1 3 5 9 7 3 2 9 6 4 8 4 2 1 5
For a hint click once; for answers click twice.

29. 5 9 3 8 6 2 1 4 7 7 2 4 1 5 3 9 8 6 N. 6 8 1 9 7 4 2 3 5 1 5 8 3 4 9 7 6 2 3 7
9 by 9 puzzle 6 5 2 1 4 9 8 2 4 9 7 8 6 5 1 3 8 1 5 6 9 7 3 2 4 9 6 2 4 3 5 8 7 1 4 3 7 2 1 8 6 5 9

30. Credits Thanks to http://sudoku.com.au/
for permission to use their puzzles,
and to
for permission to use the image on the title page.
Send feedback to