Medium Puzzle #52 - 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	1				6				8		Medium Puzzle #52 - November 21, 2005
2	9				2				3		Original puzzle as published © joe-ks.com
3	8	5			3			6	4
4	7	6			1			8	9
5	2	8			5			1	7
6		4	1		9			2	6
7			8	6	4	2	9
8				9	7	3
9					8
	A	B	C	D	E	F	G	H	I
1	1				6				8		Step 1: #6 is in Rows 1 & 3: #6 MUST go in Cell C2
2	9		6		2				3		(cf #6 in Column B @ B4 excludes use of Cell B2)
3	8	5			3			6	4
4	7	6			1			8	9		Step 2: #6 is in Rows 4 & 6: #6 MUST go in Cell F5
5	2	8			5	6		1	7		(cf #6 in Column D @ D7 excludes use of Cell D5)
6		4	1		9			2	6
7			8	6	4	2	9
8				9	7	3
9					8
	A	B	C	D	E	F	G	H	I
1	1		4		6			9	8		Step 3: #9 is in Collumns G & I: #9 MUST go in Cell H1
2	9		6		2				3		(cf #9 in Row 2 @ A2 excludes use of Cell H2)
3	8	5			3	9		6	4
4	7	6			1			8	9		Step 4: #9 is now in Rows 1 & 2: #9 MUST go in Cell F3
5	2	8			5	6		1	7		(#9 in Column D @ D8 excludes use of Cell D3)
6		4	1		9			2	6
7			8	6	4	2	9				Step 5: Block A needs #4: #4 MUST go in Cell C1
8				9	7	3					(#4 in Column B @ B6 exclude use of Cells B1 & B2, &
9					8						#4 in Row 3 @ I3 excludes use of Cell C3)
	A	B	C	D	E	F	G	H	I
1	1	3	4		6			9	8		Step 6: #2 is in Rows 5 & 6: #2 MUST go in Cell D4
2	9		6		2				3		(#2 in Column F @ F7 excludes use of Cell F4)
3	8	5			3	9		6	4
4	7	6		2	1			8	9		Step 7: #3 is in Rows 2 & 3: #3 MUST go in Cell B1...
5	2	8			5	6		1	7
6		4	1		9			2	6
7			8	6	4	2	9
8				9	7	3
9					8
	A	B	C	D	E	F	G	H	I
1	1	3	4		6		2	9	8		Step 8: Complete Block AA: need #s 2 & 7…
2	9	7	6		2				3		#2 can't go in Cell B2 (cf #2 in Row 2 @ E2), so
3	8	5	2		3	9		6	4		#2 MUST go in Cell C3, & therefore #7 MUST go in Cell B2
4	7	6		2	1			8	9
5	2	8			5	6		1	7		Step 9: #2 is now in Rows 2 & 3: #2 MUST go in Cell G1...
6		4	1		9			2	6
7			8	6	4	2	9	7			Step 10: #7 is now in Columns A & B: #7 MUST go in Cell C9
8				9	7	3					Step 11: #7 is now in Rows 8 & 9: #7 MUST go in Cell H7
9			7		8						(#7 in Column I @ I5 excludes use of Cell I7)
	A	B	C	D	E	F	G	H	I
1	1	3	4		6		2	9	8		Step 12: Block CC needs #7: #7 MUST go in Cell G3
2	9	7	6		2		1	5	3		(#7 in Row 2 @ B2 excludes use of Cells G2 & H2)
3	8	5	2	1	3	9	7	6	4
4	7	6		2	1			8	9		Step 13: Complete Block CC: need #s 1 & 5…
5	2	8			5	6		1	7		#1 can't go in Cell H2 (cf #1 in Column H @ H5), so
6		4	1		9			2	6		#1 MUST go in cell G2, & therefore #5 MUST go in Cell H2
7			8	6	4	2	9	7
8				9	7	3					Step 14: #1 is now in Rows 1 & 2: #1 MUST go in Cell D3...
9			7		8
	A	B	C	D	E	F	G	H	I
1	1	3	4		6		2	9	8		Step 15:  Complete Column H: need #s 3 & 4…
2	9	7	6		2		1	5	3		#3 can't go in Cell H8 (cf #3 in Row 8 @ F8), so
3	8	5	2	1	3	9	7	6	4		#3 MUST go in Cell H9, & therefore #4 MUST go in Cell H8
4	7	6		2	1			8	9
5	2	8			5	6		1	7		Step 16: #3 is now in Rows 8 & 9: #3 MUST go in Cell A7
6		4	1		9			2	6		(#3 in Column B @ B1 excludes use of Cell B7)
7	3		8	6	4	2	9	7
8				9	7	3		4			Step 17: #4 is now in Rows 7 & 8: #4 MUST go in Cell A9
9	4		7		8			3			(#4 in Column B @ B6 excludes use of Cell B9)
	A	B	C	D	E	F	G	H	I
1	1	3	4	7	6	5	2	9	8		Step 18:  Complete Block HH: need #s 1 & 5…
2	9	7	6		2		1	5	3		#1 can’t go in Cell D9 (cf #1 in Column D @ D3), so
3	8	5	2	1	3	9	7	6	4		#1 MUST go in Cell F9, & therefore #5 MUST go in Cell D9
4	7	6		2	1			8	9
5	2	8			5	6		1	7		Step 19: Complete Row 1: need #s 5 & 7…
6		4	1		9	7		2	6		#5 can't go in Cell D1 (cf #5 in Step 18 @ D9), so
7	3		8	6	4	2	9	7			#5 MUST go in Cell F1, & therefore # 7 MUST go in D1
8				9	7	3		4			Step 20: #7 is now in Columns D & E: #7 MUST go in Cell F6
9	4		7	5	8	1		3			(cf #7 in Row 4 @ A4 excludes use of Cell F4)
	A	B	C	D	E	F	G	H	I
1	1	3	4	7	6	5	2	9	8		Step 21: Complete Column A: need #s 5 & 6…
2	9	7	6		2		1	5	3		#6 can't go in Cell A6 (cf #6 in Row 6 @ I6), so
3	8	5	2	1	3	9	7	6	4		#6 MUST go in Cell A8, & therefore #5 MUST go in Cell A6
4	7	6		2	1			8	9
5	2	8			5	6		1	7		Step 22: #6 is now in Rows 7 & 8: #6 MUST go in Cell G9
6	5	4	1		9	7		2	6		(#6 in Column I @ I6 excludes use of Cell I9)
7	3		8	6	4	2	9	7
8	6			9	7	3		4
9	4		7	5	8	1	6	3
	A	B	C	D	E	F	G	H	I
1	1	3	4	7	6	5	2	9	8		Step 23: Complete Row 9: need #s 2 & 9…
2	9	7	6		2		1	5	3		#9 can't go in Cell I9 (cf #9 in Column I @ I4), so
3	8	5	2	1	3	9	7	6	4		#9 MUST go in Cell B9, & therefore #2 MUST go in Cell I9
4	7	6	3	2	1			8	9
5	2	8	9		5	6		1	7		Step 24: Complete Block DD: need #s 3 & 9…
6	5	4	1		9	7		2	6		#9 can't go in Cell C4 (cf #9 in Row 9 @ I9), so
7	3		8	6	4	2	9	7			#9 MUST go in Cell C5, & therefore #3 MUST go in Cell C4
8	6			9	7	3		4
9	4	9	7	5	8	1	6	3	2
	A	B	C	D	E	F	G	H	I
1	1	3	4	7	6	5	2	9	8		Step 25: Complete Column C: #5 MUST go in Cell C8...
2	9	7	6		2		1	5	3
3	8	5	2	1	3	9	7	6	4		Step 26: #5 is now in Rows 8 & 9: #5 MUST go in Cell I7...
4	7	6	3	2	1			8	9