## Stuck - Need help on next move and why?

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

### Stuck - Need help on next move and why?

5 X 2 X X 1 X 6 X
X X X 9 X 6 1 5 X
9 6 1 5 X X X 3 X
8 2 9 7 5 4 3 1 6
X 1 X 6 8 X X X 5
6 5 X X 1 9 8 X X
2 9 5 X 6 X 4 X 1
4 7 8 1 X 5 6 X 3
1 3 6 X X X 5 X X
skipper

Posts: 4
Joined: 14 February 2006

Hi

Here's your grid laid out in all it's glory with the assistance of Simple Sudoku

If you download this programme it will do the donkey work for you and leave you free to fly.

Code: Select all
`*-----------------------------------------------------------* | 5     48    2     | 348   347   1     | 79    6     4789  | | 37    48    347   | 9     2347  6     | 1     5     2478  | | 9     6     1     | 5     247   278   | 27    3     2478  | |-------------------+-------------------+-------------------| | 8     2     9     | 7     5     4     | 3     1     6     | | 37    1     347   | 6     8     23    | 279   2479  5     | | 6     5     347   | 23    1     9     | 8     247   247   | |-------------------+-------------------+-------------------| | 2     9     5     | 38    6     378   | 4     78    1     | | 4     7     8     | 1     29    5     | 6     29    3     | | 1     3     6     | 248   2479  278   | 5     2789  2789  | *-----------------------------------------------------------*`

Now you can easily see the naked pair in box 1.
Use that and you will find another in row 2.
Now look for a hidden single in column 5.
Now you're on your own, baby ...
emm

Posts: 987
Joined: 02 July 2005

### re: Stuck - Need help on next move and why?

skipper wrote:
Code: Select all
` 5 . 2 | . . 1 | . 6 .  . . . | 9 . 6 | 1 5 .  9 6 1 | 5 . . | . 3 . -------+-------+------ 8 2 9 | 7 5 4 | 3 1 6  . 1 . | 6 8 . | . . 5  6 5 . | . 1 9 | 8 . . -------+-------+------ 2 9 5 | . 6 . | 4 . 1  4 7 8 | 1 . 5 | 6 . 3  1 3 6 | . . . | 5 . . `

the 3 for box1 must be in r2; so, no other 3 in that row!
now the 3 for c5 has only one possible cell (not in r2).

( box-line interaction - or angusj calls it "Locked Candidates" )
Last edited by Pat on Fri May 26, 2006 3:28 am, edited 1 time in total.

Pat

Posts: 3550
Joined: 18 July 2005

Code: Select all
` 5 . 2 | . . 1 | . 6 .  . . . | 9 . 6 | 1 5 .  9 6 1 | 5 . . | . 3 . -------+-------+------  8 2 9 | 7 5 4 | 3 1 6  . 1 . | 6 8 . | . . 5  6 5 . | . 1 9 | 8 . . -------+-------+------  2 9 5 | . 6 . | 4 . 1  4 7 8 | 1 . 5 | 6 . 3  1 3 6 | . . . | 5 . . `

3 and 7 in box 1 must be in r2c13. In box 4 there is only three empty cells. 3 and 7 has to go in different columns, otherwise there would be no availabe candidates for r2c3. 3 and 7 cannot occupy the two cells in row 5 (UR). Therefore 3 and 7 has to go in r5c1 and r6c3, leaving r5c3=4.

RW
RW
2010 Supporter

Posts: 1000
Joined: 16 March 2006

Sorry emm, I am not that advanced. I can see 48 48 in box 1, and 37 37 in row 2, but what principle do i use to find the hidden single in column 5?
skipper

Posts: 4
Joined: 14 February 2006

The pair in row 2 eliminates the 3s and 7s from the rest of row 2, right.

Now look at what you have left.

A hidden single = the only possible place for a number in a group - hidden because it's in amongst others.

There's only one .....
emm

Posts: 987
Joined: 02 July 2005

RW wrote:3 and 7 in box 1 must be in r2c13. In box 4 there is only three empty cells. 3 and 7 has to go in different columns, otherwise there would be no availabe candidates for r2c3. 3 and 7 cannot occupy the two cells in row 5 (UR). Therefore 3 and 7 has to go in r5c1 and r6c3, leaving r5c3=4.

Nice, probably easier to spot without pm's than the box/line interaction + single
ravel

Posts: 998
Joined: 21 February 2006

This puzzle will only require box-line interactions & singles to solve, The use of doubles will cut corners at the price of increasing difficulty of technique......

tarek

tarek

Posts: 2650
Joined: 05 January 2006