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Easy Puzzle #14 - 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 5         4   9   Easy Puzzle #14 - October 14, 2005
2 4 2       5 1     One possible Solution Method follows below…
3   1 9 7 8   2 4  
4   4     1   8 7  
5       2 7   4    
6   9     6     5  
7   7 5 8     6 2  
8 2 6   9 4     3 1
9   3     5 2 9    
A B C D E F G H I
1 5         4   9   Step 1: #5 is in Rows 1 & 2: #5 MUST go in Cell I3…
2 4 2       5 1    
3   1 9 7 8   2 4 5
4   4     1   8 7   Step 2: #6 is in Rows 7 & 8: #6 MUST go in Cell D9…
5       2 7   4    
6   9     6     5  
7   7 5 8     6 2  
8 2 6   9 4     3 1
9   3   6 5 2 9    
A B C D E F G H I
1 5         4   9   Step 3: #4 is in Columns A & B: #4 MUST go in Cell C9
2 4 2       5 1          (cf #4 in Row 8 @ E8 excludes use of Cell C8)
3   1 9 7 8   2 4 5
4   4     1   8 7   Step 4: #5 is in Columns H & I: #5 MUST go in Cell G8…
5       2 7   4    
6   9     6     5  
7   7 5 8     6 2  
8 2 6   9 4   5 3 1
9   3 4 6 5 2 9    
A B C D E F G H I
1 5         4   9   Step 5: #4 is in Rows 8 & 9: #4 MUST go in Cell I7…
2 4 2       5 1    
3   1 9 7 8   2 4 5
4   4     1   8 7   Step 6: #4 is in Rows 4 & 5: #4 MUST go in Cell D6
5       2 7   4          (cf #4 in Column F @ F1 excludes use of Cell F6)
6   9   4 6     5  
7   7 5 8     6 2 4
8 2 6   9 4   5 3 1
9   3 4 6 5 2 9    
A B C D E F G H I
1 5       2 4   9   Step 7: Block HH needs #7: #7 MUST go in Cell F8
2 4 2       5 1          (#7 in Row 7 @ B7 excludes use of Cells E7 & F7)
3   1 9 7 8   2 4 5
4   4     1   8 7   Step 8: #2 is in Rows 2 & 3: #2 MUST go in Cell E1
5       2 7   4          (cf #2 in Column D @ D5 excludes use of Cell D1)
6   9   4 6     5  
7   7 5 8     6 2 4
8 2 6   9 4 7 5 3 1
9   3 4 6 5 2 9    
A B C D E F G H I
1 5       2 4   9   Step 9: Complete Block HH: need #s 1 & 3…
2 4 2       5 1          #1 can't go in Cell E7 (cf #1 in Column E @ E4), so
3   1 9 7 8   2 4 5      #1 MUST go in Cell F7, & therefore #3 MUST go in Cell E7
4   4     1   8 7  
5       2 7   4 1   Step 10: #1 is in Columns G & I: #1 MUST go in Cell H5…
6   9   4 6     5  
7   7 5 8 3 1 6 2 4
8 2 6   9 4 7 5 3 1
9   3 4 6 5 2 9    
A B C D E F G H I
1 5     1 2 4   9   Step 11: Complete Block II: need #s 7 & 8…
2 4 2       5 1          #7 can't go in Cell H9 (cf #7 in Column H @ H4), so
3   1 9 7 8   2 4 5      #7 MUST go in Cell I9, & therefore #8 MUST go in Cell H9
4   4     1   8 7  
5       2 7   4 1   Step 12: #8 is now in Rows 7 & 9: #8 MUST go in Cell C8…
6   9   4 6     5  
7   7 5 8 3 1 6 2 4 Step 13: #1 is in Rows 2 & 3: #1 MUST go in Cell D1…
8 2 6 8 9 4 7 5 3 1
9   3 4 6 5 2 9 8 7
A B C D E F G H I
1 5     1 2 4   9   Step 14: Complete Row 7: #9 MUST go in Cell A7…
2 4 2       5 1    
3   1 9 7 8   2 4 5 Step 15: Complete Row 9 (& Block GG):
4   4     1   8 7        #1 MUST go in Cell A9…
5       2 7   4 1  
6   9 1 4 6     5   Step 16: #1 is in Rows 4 & 5: #1 MUST go in Cell C6
7 9 7 5 8 3 1 6 2 4      (cf #1 from Step 15 @ A9 excludes use of Cell A6)
8 2 6 8 9 4 7 5 3 1
9 1 3 4 6 5 2 9 8 7
A B C D E F G H I
1 5     1 2 4 7 9   Step 17: Complete Column D: need #s 3 & 5…
2 4 2   3   5 1          #5 can't go in Cell D2 (cf #5 in Row 2 @ F2), so
3   1 9 7 8   2 4 5      #5 MUST go in Cell D4, & therefore #3 MUST go in Cell D2
4   4   5 1   8 7  
5       2 7   4 1   Step 18: #7 is in Columns H & I: #7 MUST go in Cell G1…
6   9 1 4 6     5  
7 9 7 5 8 3 1 6 2 4
8 2 6 8 9 4 7 5 3 1
9 1 3 4 6 5 2 9 8 7
A B C D E F G H I
1 5 8   1 2 4 7 9   Step 19: Complete Block BB: need #s 6 & 9…
2 4 2   3 9 5 1 6        #6 can't go in Cell E2 (cf #6 in Column E @ E6), so
3   1 9 7 8 6 2 4 5      #6 MUST go in Cell F3, & therefore #9 MUST go in Cell E2
4   4   5 1   8 7  
5   5   2 7   4 1   Step 20: Complete Column B: need #s 5 & 8…
6   9 1 4 6     5        #5 can't go in Cell B1 (cf #5 in Row 1 @ A1), so
7 9 7 5 8 3 1 6 2 4      #5 MUST go in Cell B5, & therefore #8 MUST go in Cell B1
8 2 6 8 9 4 7 5 3 1
9 1 3 4 6 5 2 9 8 7 Step 21: Complete Column H: #6 MUST go in Cell H2…
A B C D E F G H I
1 5 8   1 2 4 7 9 3 Step 22: Complete Block CC: need #s 3 & 8…
2 4 2   3 9 5 1 6 8      #3 can't go in Cell I2 (cf #3 in Row 2 @ D2), so
3   1 9 7 8 6 2 4 5      #3 MUST go in Cell I1, & therefore #8 MUST go in Cell I2
4   4   5 1   8 7  
5   5   2 7   4 1   Step 23: Complete Column G: #3 MUST go in Cell G6