Easy Puzzle #21 - One Possible Solution Approach…
	NB:  There is only one final solution to this Sudoku puzzle…
	Rules: Place a number from 1-9 in each empty cell so that each row, each column AND each 3x3 block contains all the numbers from 1-9.
	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			8		3		2		4		Easy Puzzle #21 - October 21, 2005
2	2	1		7	4						Original puzzle as published on joe-ks.com…
3				6	8			7
4		5			7				8
5	7	9		5	1			2
6	8		3			6	5	1
7		8		3	2		9	5
8		6			5				1
9			9	8		1	7	3
	A	B	C	D	E	F	G	H	I
1			8		3		2		4		Step 1: #2 is in Rows 1 & 2: #2 MUST go in Cell F3…
2	2	1		7	4
3				6	8	2		7
4		5			7				8		Step 2: #7 is in Rows 4 & 5: #7 MUST go in Cell I6…
5	7	9		5	1			2
6	8		3			6	5	1	7
7		8		3	2		9	5			Step 3: #3 is in Rows 7 & 9: #3 MUST go in Cell A8
8	3	6			5				1		(cf #3 in Column C @ C6 excludes use of Cell C8)
9			9	8		1	7	3
	A	B	C	D	E	F	G	H	I
1			8		3		2		4		Step 4: #3 is in Columns A & C: #3 MUST go in Cell B3
2	2	1		7	4						(cf #3 in Row 1 @ E1 excludes use of Cell B1)
3		3		6	8	2		7
4		5			7				8		Step 5: #6 is in Columns D & F: #6 MUST go in Cell E9…
5	7	9		5	1			2
6	8		3			6	5	1	7
7		8		3	2		9	5
8	3	6			5				1
9			9	8	6	1	7	3
	A	B	C	D	E	F	G	H	I
1			8		3		2		4		Step 6: Complete Column E: #9 MUST go in Cell E6…
2	2	1		7	4
3		3		6	8	2	1	7
4		5			7				8		Step 7: #1 is in Columns H & I: #1 MUST go in Cell G3
5	7	9		5	1			2			(cf #1 in Row 2 @ B2 excludes use of Cell G2)
6	8		3		9	6	5	1	7
7		8		3	2		9	5
8	3	6			5				1
9			9	8	6	1	7	3
	A	B	C	D	E	F	G	H	I
1		7	8		3		2		4		Step 8: #7 is in Rows 2 & 3: #7 MUST go in Cell B1
2	2	1		7	4						(cf #7 in Column A @ A5 excludes use of Cell A1)
3		3		6	8	2	1	7
4		5			7				8		Step 9: #6 is in Rows 8 & 9: #6 MUST go in Cell I7…
5	7	9		5	1			2
6	8		3		9	6	5	1	7
7		8		3	2		9	5	6
8	3	6			5				1
9			9	8	6	1	7	3
	A	B	C	D	E	F	G	H	I
1		7	8	1	3		2		4		Step 10: #1 is in Rows 2 & 3: #1 MUST go in Cell D1
2	2	1		7	4						(cf #1 in Column F @ F9 excludes use of Cell F1)
3		3		6	8	2	1	7
4		5			7			9	8		Step 11: #9 is in Rows 5 & 6: #9 MUST go in Cell H4
5	7	9		5	1			2			(cf #9 in Column G @ G7 excludes use of Cell G4)
6	8		3		9	6	5	1	7
7		8		3	2		9	5	6
8	3	6			5				1
9			9	8	6	1	7	3
	A	B	C	D	E	F	G	H	I
1		7	8	1	3		2		4		Step 12: Column H needs #4: #4 MUST go in Cell H8
2	2	1		7	4						(#4 in Row 1 @ I1 excludes Cell H1, & #4 in Row 2 @ E2
3		3		6	8	2	1	7			excludes Cell H2)
4		5			7			9	8
5	7	9		5	1			2
6	8		3		9	6	5	1	7
7		8		3	2		9	5	6
8	3	6			5			4	1
9			9	8	6	1	7	3
	A	B	C	D	E	F	G	H	I
1		7	8	1	3		2		4		Step 13: Complete Block II: need #s 2 & 8…
2	2	1		7	4						#8 can't go in Cell I9 (cf #8 in Row 9 @ D9), so
3		3		6	8	2	1	7			#8 MUST go in Cell G8, & therefore #2 MUST go in Cell I9
4		5			7			9	8
5	7	9		5	1			2			Step 14: Complete Column B: need #s 2 & 4…
6	8	2	3		9	6	5	1	7		#2 can't go in Cell B8 (see #2 from Step 13 @ I9), so
7		8		3	2		9	5	6		#2 MUST go in Cell B6, & therefore #4 MUST go in Cell B8
8	3	6			5		8	4	1
9		4	9	8	6	1	7	3	2
	A	B	C	D	E	F	G	H	I
1		7	8	1	3		2	6	4		Step 15: Complete Row 9: #5 MUST go in Cell A9…
2	2	1		7	4			8
3		3		6	8	2	1	7			Step 16: Complete Column H: need #s 6 & 8…
4		5			7			9	8		#8 can't go in Cell H1 (cf #8 in Row 1 @ C1), so
5	7	9		5	1			2			#8 MUST go in Cell H2, & therefore #6 MUST go in Cell H1
6	8	2	3		9	6	5	1	7
7		8		3	2		9	5	6
8	3	6			5		8	4	1
9	5	4	9	8	6	1	7	3	2
	A	B	C	D	E	F	G	H	I
1	9	7	8	1	3	5	2	6	4		Step 17: Complete Row 1: need #s 5 & 9…
2	2	1		7	4			8			#5 can’t go in Cell A1 (cf #5 in Column A @ A9), so
3		3		6	8	2	1	7			#5 MUST go in Cell F1, & therefore #9 MUST go in Cell A1
4		5			7			9	8
5	7	9		5	1			2			Step 18: Complete Row 6: #4 MUST go in Cell D6…
6	8	2	3	4	9	6	5	1	7
7		8		3	2		9	5	6
8	3	6			5		8	4	1
9	5	4	9	8	6	1	7	3	2
	A	B	C	D	E	F	G	H	I
1	9	7	8	1	3	5	2	6	4		Step 19: Complete Column D: need #s 2 & 9…
2	2	1		7	4			8			#9 can't go in Cell D4 (cf #9 in Row 4 @ H4), so
3		3		6	8	2	1	7			#9 MUST go in Cell D8, & therefore #2 MUST go in Cell D4
4		5		2	7			9	8
5	7	9		5	1			2
6	8	2	3	4	9	6	5	1	7
7		8		3	2		9	5	6
8	3	6		9	5		8	4	1
9	5	4	9	8	6	1	7	3	2
	A	B	C	D	E	F	G	H	I
1	9	7	8	1	3	5	2	6	4		Step 20: Complete Block HH: need #s 4 & 7…
2	2	1		7	4			8			#4 can't go in Cell F8 (cf #4 in Row 8 @ H8), so
3		3		6	8	2	1	7			#4 MUST go in Cell F7, & therefore #7 MUST go in Cell F8
4		5		2	7	3		9	8
5	7	9		5	1	8		2			Step 21: Complete Block EE: need #s 3 & 8…
6	8	2	3	4	9	6	5	1	7		#8 can't go in Cell F4 (cf #8 in Row 4 @ I4), so
7		8		3	2	4	9	5	6		#8 MUST go in Cell F5, & therefore #3 MUST go in Cell F4
8	3	6		9	5	7	8	4	1
9	5	4	9	8	6	1	7	3	2
	A	B	C	D	E	F	G	H	I
1	9	7	8	1	3	5	2	6	4		Step 22: Complete Column F: #9 MUST go in Cell F2…
2	2	1		7	4	9		8
3		3		6	8	2	1	7
4		5		2	7	3		9	8		Step 23: Complete Row 7: need #s 1 & 7…
5	7	9		5	1	8		2			#7 can't go in Cell A7 (cf #7 in Column A @ A5), so
6	8	2	3	4	9	6	5	1	7		#7 MUST go in Cell C7, & therefore #1 MUST go in Cell A7
7	1	8	7	3	2	4	9	5	6
8	3	6		9	5	7	8	4	1
9	5	4	9	8	6	1	7	3	2
	A	B	C	D	E	F	G	H	I
1	9	7	8	1	3	5	2	6	4		Step 24: Complete Row 8 (& Block GG):
2	2	1		7	4	9		8			#2 MUST go in Cell C8…
3		3		6	8	2	1	7
4		5	1	2	7	3		9	8		Step 25: #1 is in Rows 5 & 6: #1 MUST go in Cell C4
5	7	9		5	1	8		2			(cf #1 in Column A @ A7 excludes use of Cell A4)
6	8	2	3	4	9	6	5	1	7
7	1	8	7	3	2	4	9	5	6
8	3	6	2	9	5	7	8	4	1
9	5	4	9	8	6	1	7	3	2
	A	B	C	D	E	F	G	H	I
1	9	7	8	1	3	5	2	6	4		Step 26: Complete Column A: need #s 4 & 6…
2	2	1		7	4	9		8			#6 can't go in Cell A3 (cf #6 in Row 3 @ D3), so
3	4	3		6	8	2	1	7			#6 MUST go in Cell A4, & therefore #4 MUST go in Cell A3
4	6	5	1	2	7	3		9	8
5	7	9		5	1	8		2
6	8	2	3	4	9	6	5	1	7
7	1	8	7	3	2	4	9	5	6
8	3	6	2	9	5	7	8	4	1
9	5	4	9	8	6	1	7	3	2
	A	B	C	D	E	F	G	H	I
1	9	7	8	1	3	5	2	6	4		Step 27: Complete Row 3: need #s 5 & 9…
2	2	1		7	4	9		8			#9 can't go in Cell C3 (cf #9 in Column C @ C9), so
3	4	3	5	6	8	2	1	7	9		#9 MUST go in Cell I3, & therefore #5 MUST go in Cell C3
4	6	5	1	2	7	3		9	8
5	7	9		5	1	8		2
6	8	2	3	4	9	6	5	1	7
7	1	8	7	3	2	4	9	5	6
8	3	6	2	9	5	7	8	4	1
9	5	4	9	8	6	1	7	3	2
	A	B	C	D	E	F	G	H	I
1	9	7	8	1	3	5	2	6	4		Step 28: Complete Column C: need #s 4 & 6…
2	2	1	6	7	4	9		8	5		#4 can't go in Cell C2 (cf #4 in Row 2 @ Cell E2), so
3	4	3	5	6	8	2	1	7	9		#4 MUST go in Cell C5, & therefore #6 MUST go in Cell C2
4	6	5	1	2	7	3		9	8
5	7	9	4	5	1	8		2	3		Step 29: Complete Column I: need #s 3 & 5…
6	8	2	3	4	9	6	5	1	7		#5 can't go in Cell I5 (cf #5 in Row 5 @ D5), so
7	1	8	7	3	2	4	9	5	6		#5 MUST go in Cell I2, & therefore #3 MUST go in Cell I5
8	3	6	2	9	5	7	8	4	1
9	5	4	9	8	6	1	7	3	2
	A	B	C	D	E	F	G	H	I
1	9	7	8	1	3	5	2	6	4		Step 30: Complete Row 2 (& Block CC):
2	2	1	6	7	4	9	3	8	5		#3 MUST go in Cell G2…
3	4	3	5	6	8	2	1	7	9
4	6	5	1	2	7	3	4	9	8		Step 31: Complete Row 4: #4 MUST go in Cell G4,,,
5	7	9	4	5	1	8	6	2	3
6	8	2	3	4	9	6	5	1	7		Step 32: Complete Row 5 (& Block FF & Puzzle):
7	1	8	7	3	2	4	9	5	6		#6 MUST go in Cell G5.
8	3	6	2	9	5	7	8	4	1
9	5	4	9	8	6	1	7	3	2
	A	B	C	D	E	F	G	H	I
1	9	7	8	1	3	5	2	6	4	45	Final Proof:
2	2	1	6	7	4	9	3	8	5	45	- All Rows add up to 45;
3	4	3	5	6	8	2	1	7	9	45
4	6	5	1	2	7	3	4	9	8	45
5	7	9	4	5	1	8	6	2	3	45
6	8	2	3	4	9	6	5	1	7	45
7	1	8	7	3	2	4	9	5	6	45
8	3	6	2	9	5	7	8	4	1	45
9	5	4	9	8	6	1	7	3	2	45
	45	45	45	45	45	45	45	45	45		- All Columns add up to 45;
	45			45			45				- All 3x3 Blocks add up to 45…
	45			45			45
	45			45			45