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Very hard Sudoku grids

Puzzle number 1

Hits: 7

	6		3				9
					2		8
4		3			7
9					5
		6		8		4
			1					6
			4			2		7
	3		2
	9				1		5

• Calls single candidate 16 times
• Calls candidate lines 3 times
• Calls hidden pairs / triples / etc 1 time
• Calls Forcing chains 1 time

Puzzle number 2

Hits: 5

7		8			5		1
5		9	4	1
3	1			9	7
			5	6		1
1	8			7			3	5
				4	1
8		1	7	5			2	4
				8	6			1
	9		1		4	7		8

• Calls single candidate 4 times
• Calls candidate lines 2 times
• Calls naked pairs / triples / etc 3 times
• Calls X-Wing, etc 1 time
• Calls Simple coloring 1 time
• Calls Multi coloring 2 times
• Calls Forcing chains 1 time

Puzzle number 3

Hits: 18

4			8			7
		3					2
	5			7				8
		1		9		4
6					8			5
	4		2				7
	6							4
		8		2		6
9					1			3

• Calls single candidate 12 times
• Calls naked pairs / triples / etc 2 times
• Calls Multi coloring 1 time

Puzzle number 4

Hits: 11

9	7			5				8
		8	6					2
			3	9			1
						8	2
8		7		2		1		6
	4	3
	3			8	4
6					5	9
7				6			8	1

• Calls single candidate 10 times
• Calls candidate lines 2 times
• Calls naked pairs / triples / etc 1 time
• Calls X-Wing, etc 1 time

Puzzle number 5

Hits: 10

	2	6				3		4
1	7	4	3	9	2	6	5	8
		3				2		1
7	4	1	2	8	9	5	6	3
	6	9	5		1		2	7
2		5	7		6		1	9
4		8
	5	2		7		1	4	6
6		7		2		9	8	5

• Calls candidate lines 1 time
• Calls Forcing chains 1 time

Puzzle number 6

Hits: 17

9	7		4		2		3
1				5				4
			9			7
8		4			5			7
	5						6
3			2			4		5
		8			6
5				4				8
	6		5		8		4	3

• Calls single candidate 16 times
• Calls candidate lines 1 time
• Calls naked pairs / triples / etc 1 time
• Calls X-Wing, etc 1 time

Puzzle number 7

Hits: 2

					8	9	3
				2			7	5
5			3		7			2
	1
3	8	6				4	2	1
							6
6			2		9			3
1	5			4
	3	4	5

• Calls single candidate 8 times
• Calls candidate lines 1 time
• Calls naked pairs / triples / etc 1 time
• Calls Forcing chains 1 time

Puzzle number 8

Hits: 1

	4						9
2			9		1			3
		9				4
	9			7			2
			8	3	9
	5			2			8
		6				8
3			7		8			9
	2						5

• Calls single candidate 7 times
• Calls candidate lines 1 time
• Calls naked pairs / triples / etc 1 time
• Calls Simple coloring 1 time
• Calls Forcing chains 1 time

Puzzle number 9

Hits: 5

9	7			5				8
		8	6				9	2
			3	9	8		1
						8	2
8		7		2		1		6
	4	3
	3			8	4
6					5	9
7				6			8	1

• Calls single candidate 8 times
• Calls candidate lines 2 times
• Calls naked pairs / triples / etc 1 time
• Calls X-Wing, etc 1 time

Puzzle number 10

Hits: 1

	1	2	3		6	9	4	5
	6			2				7
		3			1	6	2	8
2		6	1		8			9
				3			6	2
3			2	6	7	5		4
1		4	5		3	2	9	6
9	2	5	6	1	4			3
6	3			9	2	4	5	1

• Calls single candidate 1 time
• Calls candidate lines 1 time
• Calls naked pairs / triples / etc 1 time
• Calls Simple coloring 1 time
• Calls Forcing chains 1 time

Also in this section

• Sudoku Home
• Sudoku Solver
• Sample Easy Grids
• Sample Intermediate Grids
• Sample Hard Grids
• Sample Very Hard Grids
• Sample Diabolical Grids
• Unsolved Grids
• Unsolved Example Grid 1
• Unsolved Example Grid 2

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Copyright © Richard C Smith 2007 - 2010. This work is licenced under a Creative Commons Licence.