Medium Puzzle #40 - 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	2	8					Medium Puzzle #40 - November 9, 2005
2			5		1		2				Original puzzle as published © joe-ks.com
3		4		5		6		7
4	5				4				7
5		8		2		3		5
6	1				8				9
7		6		7		4		9
8			7		6		4
9				9	5	1
	A	B	C	D	E	F	G	H	I
1				3	2	8					Step 1: #5 is in Columns A & C: #5 MUST go in Cell B8
2			5	4	1		2				(#5 in Row 9 @ E9 excludes use of Cell B9)
3		4		5		6		7
4	5				4				7		Step 2: #4 is in Columns E & F: #4 MUST go in Cell D2...
5		8		2		3		5
6	1				8				9		Step 3: #7 is in Column H & I: #7 MUST go in Cell G9
7		6		7		4		9			(#7 in Row 7 @ D7 excludes use of Cell G7)
8		5	7		6		4
9				9	5	1	7
	A	B	C	D	E	F	G	H	I
1				3	2	8					Step 4: Complete Block BB: need #s 7 & 9…
2			5	4	1	7	2				#7 can't go in Cell E3 (cf #7 in Row 3 @ H3), so
3		4		5	9	6		7			#7 MUST go in Cell F2, & therefore #9 MUST go in Cell E3
4	5				4	9			7
5		8		2		3		5			Step 5: #9 is now in Columns D & E: #9 MUST go in Cell F4
6	1				8				9		(#9 in Row 6 @ I6 excludes use of Cell F6)
7		6		7		4		9
8		5	7		6		4
9				9	5	1	7
	A	B	C	D	E	F	G	H	I
1				3	2	8	9				Step 6: Complete Column F: need #s 2 & 5…
2			5	4	1	7	2				#5 can't go in Cell F8 (cf #5 in Row 8 @ B8), so
3		4		5	9	6		7			#5 MUST go in Cell F6, & therefore #2 MUST go in Cell F8
4	5				4	9			7
5		8		2		3		5			Step 7: #9 is in Column H & I: #9 MUST go in Cell G1
6	1				8	5			9		(#9 in Row 3 @ E3 excludes use of Cell G3)
7		6		7		4		9
8		5	7		6	2	4
9				9	5	1	7
	A	B	C	D	E	F	G	H	I
1				3	2	8	9		5		Step 8: #5 is in Rows 2 & 3: #5 MUST go in Cell I1
2			5	4	1	7	2				(#5 in Column H @ H5 excludes use of Cell H1)
3		4		5	9	6		7
4	5				4	9			7		Step 9: #5 is now in Columns H & I: #5 MUST go in Cell G7...
5		8		2		3		5
6	1				8	5			9		Step 10: Complete Block HH: need #s 3 & 8…
7		6		7	3	4	5	9			#8 can't go in Cell E7 (cf #8 in Column E @ E6), so
8		5	7	8	6	2	4				#8 MUST go in Cell D8, & therefore #3 MUST go in Cell E7
9				9	5	1	7
	A	B	C	D	E	F	G	H	I
1				3	2	8	9		5		Step 11: Complete Column E: #7 MUST go in Cell E5...
2			5	4	1	7	2
3		4		5	9	6		7			Step 12: Complete Block EE: need #s 1 & 6…
4	5			1	4	9			7		#1 can't go in Cell D6 ( cf #1 in Row 6 @ A6), so
5		8		2	7	3		5			#1 MUST go in Cell D4, & therefore #6 MUST go in Cell D6
6	1			6	8	5			9
7		6		7	3	4	5	9			Step 13: #9 is in Rows 7 & 9: #9 MUST go in Cell A8...
8	9	5	7	8	6	2	4
9				9	5	1	7
	A	B	C	D	E	F	G	H	I
1		1		3	2	8	9		5		Step 14: Block GG needs #1: #1 MUST go in Cell C7
2			5	4	1	7	2				(#1 in Column A @ A6 excludes use of Cells A7 & A9, &
3		4		5	9	6		7			#1 in Row 9 @ F9 further exludes use of Cell B9 & C9)
4	5			1	4	9			7
5		8		2	7	3		5			Step 15: #7 is in Rows 4 & 5: #7 MUST go in Cell B6
6	1	7		6	8	5			9		(#7 in Column C @ C8 excludes use of Cell C6)
7		6	1	7	3	4	5	9
8	9	5	7	8	6	2	4				Step 16: #1 is now in Columns A & C: #1 MUST go in Cell B1
9				9	5	1	7				(#1 in Row 2 @ E2 excludes use of Cell B2)
	A	B	C	D	E	F	G	H	I
1	7	1		3	2	8	9		5		Step 17: #7 is now in Columns B & C: #7 MUST go in Cell A1
2			5	4	1	7	2				(#7 in Row 2 @ F2 excludes use of Cell A2, & #7 in Row 3
3		4		5	9	6		7			@ H3 excludes use of Cell A3)
4	5			1	4	9			7
5		8	9	2	7	3		5			Step 18: #9 is in Rows 4 & 6: #9 MUST go in Cell C5
6	1	7		6	8	5			9		(#9 in Column A @ A8 excludes use of Cell A5)
7		6	1	7	3	4	5	9
8	9	5	7	8	6	2	4
9				9	5	1	7
	A	B	C	D	E	F	G	H	I
1	7	1		3	2	8	9	4	5		Step 19: #9 is in Columns A & C: #9 MUST go in Cell B2...
2		9	5	4	1	7	2
3		4		5	9	6		7			Step 20: #4 is in Rows 2 & 3: #4 MUST go in Cell H1...
4	5			1	4	9			7
5		8	9	2	7	3		5	4		Step 21: #4 is now in Columns G & H: #4 MUST go in Cell I5...
6	1	7	4	6	8	5			9
7		6	1	7	3	4	5	9			Step 22: #4 is now in Rows 4 & 5: #4 MUST go in Cell C6...
8	9	5	7	8	6	2	4
9				9	5	1	7
	A	B	C	D	E	F	G	H	I
1	7	1		3	2	8	9	4	5		Step 23: Complete Row 6: need #s 2 & 3…
2		9	5	4	1	7	2				#2 can't go in Cell G6 (cf #2 in Column G @ G2), so
3		4		5	9	6		7			#2 MUST go in Cell H6, & therefore #3 MUST go in Cell G6
4	5			1	4	9			7
5	6	8	9	2	7	3	1	5	4		Step 24: #1 is in Rows 4 & 6: #1 MUST go in Cell G5...
6	1	7	4	6	8	5	3	2	9
7		6	1	7	3	4	5	9			Step 25: Complete Row 5: #6 MUST go in Cell A5…
8	9	5	7	8	6	2	4
9