solve

 

 sudoku

   <home for links to the tutorials
explanations:-
tip 1 - three in a bed ( or Love Island ! )


This is the 'tough' puzzle from the Daily Telegraph on 21st. May 2005 which has good examples of what I call '3 in a bed'

Take the 3x3 boxes 1, 4 and 7. The 4 in c1r1 means that a 4 must be in c2 of box 7.
Therefore, there is only one place for a 4 in box4 and c3 which is c3r5

Similarly, in 3x3 boxes 3, 6 & 9 there is only one place for a 9 in c7r5 as there must be a 9 in column 8 of box 3.

Knowing where a number can't go is just as valuable as knowing where it can go.
c1
c2
c3
  
c4
c5
c6
  
c7
c8
c9
  
 
4
 

 
 
 
 
8
 
 
 
1
 
 9?
 
r1
 box

1
2
&
3
 
1
box 1 
 
 
 
box 2 
 
6		  
 
7
box 3 
 9?
 
5
r2
 
 
 
 
 
9
 
 
 
 
2
 
 9?
 
r3
 
 
 
9		  
 
4
 
 
5		  
 
6
 
 
2
r4
 box

4
5
&
6
 
box 4 
 
 
 
box 5 
 
 
 
box 6 
 
9
r5
 
6
 
 
1		  
 
2
 
 
8		  
 
3
 
 
r6
 
 
4?
 
5		  
 
 
 
9		  
 
 
 
r7
 box

7
8
&
9
 
8
box 7 
4?
 
6		  
 
box 8 
 
 
 
box 9 
 
9
r8
 
 
4?
 
2		  
 
 
6
 
 
 
 
 
7
r9



___________________________________


15th january 2010 © 2014