Diabolical Puzzle #50 - One Possible Solution Approach…
	NB:  There is only one final solution to this Sudoku puzzle…
	A	B	C	D	E	F	G	H	I
1
2	AA			BB			CC				Reference to 3x3 Blocks AA, BB & CC
3
4
5	DD			EE			FF				Reference to 3x3 Blocks DD, EE & FF
6
7
8	GG			HH			II				Reference to 3x3 Blocks GG, HH & II
9
	A	B	C	D	E	F	G	H	I
1			3				6				Diabolical Puzzle #50 - November 19, 2005
2	7	5						2	1		Original puzzle as published © joe-ks.com
3
4			7		2		5
5		4	1				2	6
6	2	9						4	3
7		8	5				9	7
8		2	6	7		1	3	8
9				8		5
	A	B	C	D	E	F	G	H	I
1			3				6				Step 1: #7 is in Columns A & C: #7 MUST go in Cell B9...
2	7	5						2	1
3								3			Step 2: #3 is in Columns G & I: #3 MUST go in Cell H3
4			7		2		5				(#3 in Row 1 @ C1 excludes use of Cell H1)
5		4	1				2	6
6	2	9						4	3
7		8	5				9	7
8		2	6	7		1	3	8
9		7		8		5
	A	B	C	D	E	F	G	H	I
1		1	3				6				Step 3: #s possible for blank cells…
2	7	5						2	1
3								3
4			7		2		5
5		4	1				2	6
6	2	9	8					4	3
7		8	5				9	7
8		2	6	7		1	3	8
9		7		8		5		1
	A	B	C	D	E	F	G	H	I
1		1	3				6				Step 4: #1 is in Rows 8 & 9: #1 MUST go in Cell A7...
2	7	5						2	1
3								3
4			7		2		5
5		4	1				2	6
6	2	9	8					4	3
7	1	8	5				9	7
8		2	6	7		1	3	8
9		7		8		5		1
	A	B	C	D	E	F	G	H	I
1		1	3				6				Step 5: #s possible for blank cells…
2	7	5						2	1		Unique #s in Blue…
3		6						3			i.e. For Cell B3, look at #s in: Block AA (1,3,7,5),
4			7		2		5	9			Row 3 (3), & Column B (1,5,4,9,8,2,7)
5		4	1				2	6			Therefore, only #6 can go in Cell B3…
6	2	9	8					4	3
7	1	8	5				9	7			… similarly for unique #s:
8		2	6	7		1	3	8			#9 in Cell H4;  and  #4 in Cell G9
9		7		8		5	4	1
	A	B	C	D	E	F	G	H	I
1		1	3				6	5			Step 6: #5 is in Rows 7 & 9: #5 MUST go in Cell I8...
2	7	5						2	1
3		6						3			Step 7: #5 is now in Columns G & I: #5 MUST go in Cell H1...
4			7		2		5	9
5		4	1				2	6
6	2	9	8					4	3
7	1	8	5				9	7
8		2	6	7		1	3	8	5
9		7		8		5	4	1
	A	B	C	D	E	F	G	H	I
1		1	3				6	5			Step 7: #s possible for blank cells…
2	7	5					8	2	1		Unique #s in Blue…
3		6						3			#8 in G2; #3 in B4; #8 in I4; #9 in C9
4		3	7		2		5	9	8
5		4	1				2	6
6	2	9	8					4	3
7	1	8	5				9	7
8		2	6	7		1	3	8	5
9		7	9	8		5	4	1
	A	B	C	D	E	F	G	H	I
1		1	3				6	5			Step 8: #s possible for blank cells…
2	7	5	4				8	2	1		Unique #s in Blue…
3		6					7	3			#4 in C2; #7 in G3; #6 in A4; #5 in A5; #7 in I5; #4 in A8; and
4	6	3	7		2		5	9	8		#3 in A9
5	5	4	1				2	6	7
6	2	9	8					4	3
7	1	8	5				9	7
8	4	2	6	7		1	3	8	5
9	3	7	9	8		5	4	1
	A	B	C	D	E	F	G	H	I
1		1	3				6	5			Step 9: #2 is in Columns A & B: #2 MUST go in Cell C3…
2	7	5	4				8	2	1
3		6	2				7	3			Step 10: Complete Column G: #1 MUST go in Cell G6...
4	6	3	7		2		5	9	8
5	5	4	1				2	6	7		Step 11: #9 is in Rows 7 & 9: #9 MUST go in Cell E8…
6	2	9	8				1	4	3
7	1	8	5				9	7
8	4	2	6	7	9	1	3	8	5
9	3	7	9	8		5	4	1
	A	B	C	D	E	F	G	H	I
1		1	3				6	5			Step 12: #s possible for blank cells…
2	7	5	4				8	2	1		Unique #s in Blue…
3		6	2				7	3			#4 in F4; #6 in E9
4	6	3	7	1	2	4	5	9	8
5	5	4	1				2	6	7		Step 13: Complete Row 9: #2 MUST go in Cell I9...
6	2	9	8				1	4	3
7	1	8	5				9	7			Step 14: #1 is in Rows 5 & 6: #1 MUST go in Cell D4...
8	4	2	6	7	9	1	3	8	5
9	3	7	9	8	6	5	4	1	2
	A	B	C	D	E	F	G	H	I
1		1	3				6	5			Step 14: #s possible for blank cells…
2	7	5	4		3		8	2	1		Unique #s in Blue…
3		6	2				7	3			#3 in E2; #8 in E5; #$ in E7; #6 in I7
4	6	3	7	1	2	4	5	9	8
5	5	4	1		8		2	6	7
6	2	9	8				1	4	3
7	1	8	5		4		9	7	6
8	4	2	6	7	9	1	3	8	5
9	3	7	9	8	6	5	4	1	2
	A	B	C	D	E	F	G	H	I
1		1	3		7		6	5			Step 15: #s possible for blank cells…
2	7	5	4		3		8	2	1		Unique #s in Blue…
3		6	2				7	3			#7 in E1;
4	6	3	7	1	2	4	5	9	8
5	5	4	1		8		2	6	7		Step 16: #7 is now in Columns D & E: #7 MUST go in Cell F6
6	2	9	8			7	1	4	3		(#7 in Row 5 @ I5 excludes use of Cell F5)
7	1	8	5		4		9	7	6
8	4	2	6	7