solve

 sudoku

   step 1 2 3 4 5 6 7 8 9 10
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A very easy puzzle to get the idea of how sudoku is solved
© Roger Walker
explanations:-
this is step 8


With 6's in c7 and c8 and row 1 there is only one place for a 6 in box 3 at c9r3 and the new 6 together with 6's in c6 and c2 fix the 6 in box 1 at c3r2.

The 6's in r4 and r6 with the 6 in c2 fix the 6 box 4 at c1r5.

Box 4 now has only two cells free for a 1 or a 2. Because r6 already has a 1 in it, cell c2r6 must be a 2 leaving c2r5 for the 1. (entered in step 9)

.Now we know the 1 in box 4 has to be in c2, the 1's in c3 and r7 position the 1 in box 7 in cell c1r9

This leaves two cells free in box 7 for a 2 and 7. c3 already has a 7 so c3r9 must be a 2 and therefore c1r7 a 7 and then only one space left in row 7 for a 2 (entered in step 9)

 
c1
c2
c3
  
c4
c5
c6
  
c7
c8
c9
 
 
6
 4
   
5 		 
9
   
6
3		  
6
r1
 box

1
2
&
3
 
3 		-box 1-
6
  
6 		   
 -box 2-
4 		 
  
9		 - box 3 
6
5
r2

8		  
5 		  
9		  
7 		 
  
    
6
4		  
6
r3

9
8
3		    
4
2		  
1		  
 		  
5
7
r4
 box

4
5
&
6
 
6 		- box 4 
6
4 		 
8		 - box 5 -
7
5 		   
 - box 6 
9
 
r5

5 		 
6
7 		 
3

9 		 
1		  
8
4
r6
 
1
3		  
8 		 

5 		 
   4

9
r7
 box

7
8
&
9

4 		- box 7 
9
5		  
6		 - box 8
 
  
  		box 9 
 
 
r8
 
1

1 		 
9
8
4 		 
5
 
 
r9




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15th january 2010 © 2014