The New Sudoku Players' Forum

[DoubleB72]

65* 743 ***
*** 296 5*7
97* *8* *6*

1** **9 3**
*9* *** *1*
**6 8** **2

*8* *** *75
5*7 9*8 ***
3** 457 *2*

Don't know what my problem is?

Thanks

[Lardarse]

Hidden single in row 4.
Some locked canddates in box 1 exclude candidates in the rest of column 3.
Then another hidden single in row 4.

[QBasicMac]

Where do you go from here and why can't I see it

I assume you did this:

Started with a pencilmark grid like the one below:

Code: Select all

+-------------------+----------------+-----------------+
| 6     5     128   | 7    4     3   | 1289  89   189  |
| 48    134   1348  | 2    9     6   | 5     348  7    |
| 9     7     1234  | 15   8     15  | 124   6    134  |
+-------------------+----------------+-----------------+
| 1     24    2458  | 56   267   9   | 3     458  468  |
| 2478  9     23458 | 356  2367  245 | 4678  1    468  |
| 47    34    6     | 8    137   145 | 479   459  2    |
+-------------------+----------------+-----------------+
| 24    8     1249  | 136  1236  12  | 1469  7    5    |
| 5     1246  7     | 9    1236  8   | 146   34   1346 |
| 3     16    19    | 4    5     7   | 1689  2    1689 |
+-------------------+----------------+-----------------+


Noted all 2 occurrences of candidate 1 in box 2 fall on row 3. Therefore the other cells on row 3 cannot contain a 1. It must go in box 2. That is called Locked Candidate 1 in box 2.
Therefore you erased 1 from columns 3, 7, and 9.

Saw newly Locked Candidate 1 in box 3 and thus erased 1 from r1c3

Saw Locked Candidate 2 in box 1 (column 3) and erased some 2's

Saw Locked Candidate 3 in box 9...

If so, that got you to here:

Code: Select all

+------------------+----------------+-----------------+
| 6     5     28   | 7    4     3   | 1289  89   189  |
| 48    134   1348 | 2    9     6   | 5     348  7    |
| 9     7     234  | 15   8     15  | 24    6    34   |
+------------------+----------------+-----------------+
| 1     24    458  | 56   267   9   | 3     458  468  |
| 2478  9     3458 | 356  2367  245 | 4678  1    468  |
| 47    34    6    | 8    137   145 | 479   459  2    |
+------------------+----------------+-----------------+
| 24    8     149  | 136  1236  12  | 1469  7    5    |
| 5     1246  7    | 9    126   8   | 146   34   1346 |
| 3     16    19   | 4    5     7   | 1689  2    1689 |
+------------------+----------------+-----------------+


Look at row 4. It has only one candidate 7. You can place it. Just keep doing stuff like that.

If you are using pencilmarks as shown, please post your pencilmarks when you have a question and we can see for sure where you are stuck and not have to guess.

If you are NOT using the pencilmark technique, then you probably need to find a book with easier puzzles. This one is too difficult for me, at least, to solve without pencilmarks.

Mac

[DoubleB72]

I do use pencil marks and had all the same, I just didn't see the obvious.

Thanks