## Slightly hard puzzle

Post the puzzle or solving technique that's causing you trouble and someone will help

### Slightly hard puzzle

I'm stuck at this point on this puzzle and was hoping someone could suggest a next step. Thanks in advance!! Jay.

5 x x | 6 x x | x x 1
1 6 7 | 5 x x | 9 x 4
8 x x | x 1 x | x 5 6
------+-------+------
4 1 6 | x x x | 8 x 9
3 x 5 | x x x | 1 x 2
2 x 9 | x x x | x 4 5
------+-------+------
6 x 8 | x 9 x | 4 x 3
9 x 4 | x x 8 | 5 x 7
7 x 1 | x x 4 | x 9 8
5krunner

Posts: 22
Joined: 19 December 2005

The key to solving it is column 4.

Pencilmarks for the grid: (note: these are the initial pencilmarks. Some canidates can be removed. (for example the 2 and the 3 in r1c2 and r3c2.)
Code: Select all
`5  2349  23 | 6      23478  2379 | 237  2378  11  6     7  | 5      238    23   | 9    238   48  2349  23 | 23479  1      2379 | 237  5     6------------+--------------------+-------------4  1     6  | 237    2357   2357 | 8    37    93  78    5  | 4789   4678   679  | 1    67    22  78    9  | 1378   3678   1367 | 367  4     5------------+--------------------+-------------6  25    8  | 127    9      1257 | 4    12    39  23    4  | 123    236    8    | 5    126   77  235   1  | 23     2356   4    | 26   9     8`

If you look carefully at column 4 then you see a hidden triple and a naked quad.

The triple: 489: there are exactly three cells that can have one of those 3 numbers. (r3c4, r5c4, r6c4)
Naked quad: 1237: there are exactly 4 cells that share the same 4 candidates. (r4c4, r7c4, r8c4, r9c4)

This allows you to remove the following candidates:
• 237 from r3c4 leaving 49
• 7 from r5c4 leaving 489
• 137 from r6c4 leaving 8

Leaving you with this grid:
Code: Select all
`5  2349  23 | 6      23478  2379 | 237  2378  11  6     7  | 5      238    23   | 9    238   48  2349  23 | 49     1      2379 | 237  5     6------------+--------------------+-------------4  1     6  | 237    2357   2357 | 8    37    93  78    5  | 489    4678   679  | 1    67    22  78    9  | 8      3678   1367 | 367  4     5------------+--------------------+-------------6  25    8  | 127    9      1257 | 4    12    39  23    4  | 123    236    8    | 5    126   77  235   1  | 23     2356   4    | 26   9     8`
Last edited by Animator on Mon Apr 17, 2006 9:00 am, edited 1 time in total.
Animator

Posts: 469
Joined: 08 April 2005

### Slightly hard puzzle

Animator,

That's amazing ... I see the the triple and quad now you mentioned ... would have had a hard time seeing that on my own. I have a way to go to master these harder puzzles. Thank you!!!

Jay.
5krunner

Posts: 22
Joined: 19 December 2005

Animator wrote:The key to solving it is column 4.

col 4 has a hidden double {49}
gsf
2014 Supporter

Posts: 7306
Joined: 21 September 2005
Location: NJ USA

I see that too now!! Thanks!! I need to be able to spot these myself.
5krunner

Posts: 22
Joined: 19 December 2005

If you look at the 6's in box 8, you'll find that they are locked in column 5, so you can remove the 6's in box 5, r5c5 and r6c5.

MCC
MCC

Posts: 1275
Joined: 08 June 2005