The New Sudoku Players' Forum

[LBJOHN]

Code: Select all

+---+---+---+
|819|263|547|
|756|48.|3..|
|243|57.|...|
+---+---+---+
|3.1|...|...|
|.24|1.7|.8.|
|...|...|..1|
+---+---+---+
|...|..4|15.|
|4.5|.1.|..6|
|1.2|.56|794|
+---+---+---+

[emm]

Hi LBJ - naked pairs in column 6 and then row 8 are the key to unlocking this puzzle.

Naked pair = If the same two numbers are the only two numbers in two cells in a row, column or box then you can remove them from all other cells in that row, column or box.

Hint - which two numbers can only go in the last two cells in box 2?

[LBJOHN]

Call me stupid. But which is the next number that you can write in. Please simply reply with a number and the reason.

[Shazbot]

Your beginning candidates for r8c6 are 2, 8 and 9. The only places for 1 and 9 to go in box 2 are in column 6, so the 9 can be eliminated from r8c6, leaving 2 and 8. 2 and 8 are also the only candidates for r8c7, so you can remove them from all other cells in row 8. This leaves 3 as the only candidate for r8c8.

Code: Select all

 *-----------*
 |819|263|547|
 |756|48.|3..|
 |243|57.|...|
 |---+---+---|
 |3.1|...|...|
 |.24|1.7|.8.|
 |...|...|..1|
 |---+---+---|
 |...|..4|15.|
 |4.5|.1.|.36|
 |1.2|.56|794|
 *-----------*

 
 *--------------------------------------------------------------------*
 | 8      1      9      | 2      6      3      | 5      4      7      |
 | 7      5      6      | 4      8      19     | 3      12     29     |
 | 2      4      3      | 5      7      19     | 689    16     89     |
 |----------------------+----------------------+----------------------|
 | 3      6789   1      | 689    249    258    | 2469   267    259    |
 | 569    2      4      | 1      39     7      | 69     8      359    |
 | 569    6789   78     | 3689   2349   258    | 2469   267    1      |
 |----------------------+----------------------+----------------------|
 | 69     36789  78     | 3789   239    4      | 1      5      28     |
 | 4      79     5      | 79     1      28     | 28     3      6      |
 | 1      38     2      | 38     5      6      | 7      9      4      |
 *--------------------------------------------------------------------*


After this, your next step is to see where a 3 can go in column 9.