solve

 sudoku

  to step 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
  <home

explanations:-
this is step:- 16


Now work down boxes 1, 4 & 7 and for each empty cell note all numbers missing from its row, column and box. For example, in the top left cell it has 1358 in its row ; and 1468 in its column ; and 134 in its box. This leaves 2, 7 or 9 as possibles.


Only 2 cells left in box 6 so they must be 4 or 5

c1
c2
c3
 
c4
c5
c6
 
c7
c8
c9
 
279 
 
3
6 279
 
 
5
 
 9
 
 
8
 
1
 
r1
box

1
2
&
3
 
1
258 
258 
 
 
7
box 2 
6
8
 
 
box 3 
9
 
r2
 
4
578 
6 5789
 
 
2
 
1
 8 9
 
 
 
 
r3
 
8
 
4
 
3
 
 
9
 
7
 
5
 
 
1
 
2
 
6
r4
box

4
5
&
6
 9 25
box 4 
1
9 25 
 
 
6
3
 
4 5 
box 6 
7
 
8
r5
 
6
 7 25
7 25 
 
 
8
 
 
1
 
 
9
 
3
 4 5
r6
23 
 8 2
24  8
 
 
1
 
5
 
7
 
 
9
r7
box

7
8
&
9
2375 
box 7 
9
4  257
 
3 4 
box 8 
8
 
6
 
 
box 9 
 
1
r8
357 
 
6
 
1
 
 3 4
 
9
 
2
 
 
 
8
 
r9



___________________________________


15th january 2010 © 2014