The New Sudoku Players' Forum

[LBJOHN]

Code: Select all

+---+---+---+
|...|347|...|
|2..|..6|4.7|
|.74|.28|..5|
+---+---+---+
|..3|4.1|..2|
|429|.63|8.1|
|7..|2.9|3..|
+---+---+---+
|5..|6.2|.1.|
|1.2|.35|..9|
|...|.14|...|
+---+---+---+

The next number should be (4 or 6) in R6C8 or R6C9. Please help with the logic.

[Shazbot]

Code: Select all

 *------------------------------------------------------------------------*
 | 689     15689   1568    | 3     4       7    | 1269    2689    68      |
 | 2       13589   158     | 159   59      6    | 4       389     7       |
 | 369     7       4       | 19    2       8    | 169     369     5       |
 |-------------------------+--------------------+-------------------------|
 | 68      568     3       | 4     578     1    | 5679    5679    2       |
 | 4       2       9       | 57    6       3    | 8       57      1       |
 | 7       1568    1568    | 2     58      9    | 3       456     46      |
 |-------------------------+--------------------+-------------------------|
 | 5       3489    78      | 6     789     2    | 7       1       348     |
 | 1       468     2       | 78    3       5    | 67      4678    9       |
 | 3689    3689    678     | 789   1       4    | 2567    235678  368     |
 *------------------------------------------------------------------------*


Actually your next number would be the naked single in box 9 (a cell where only one number can go - it's actually shown above, but missing in your grid)

That leads you to a number of other naked singles, and eventually you'll be able to place a 6 in r6c9. A couple of moves before that you might notice that the 4 in r6c8 becomes a hidden single (only cell in that column that can contain that number).