## Hard Medium

Advanced methods and approaches for solving Sudoku puzzles

### Hard Medium

Newbie stuck on this one. Maybe I need to sleep on it.

*52*8173*
*38**7***
7412368**
183*2***7
2***7***8
57**982*3
425869371
3**71*58*
817****6*

Thx. for any help.

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Paulie

Posts: 10
Joined: 08 August 2005

Have a good look at column 8. There is a cell which is the only place one candidate can go.
SteveF

Posts: 86
Joined: 26 March 2005

Look at r2c8, '2' is the only possible digits in the column, so r2c8 = '2'. r2c7 = '1' because it is the only digit in the row. Look at r1c9 and r2c9, '4' and '6' are the only digits in that block, so (r1c9, r2c9) = (4, 6) -- naked pair. So r3c9 = 5 ......

Posts: 62
Joined: 15 July 2005

### I've seen the light

Thx. guys for unblocking my mental block.
Paulie

Posts: 10
Joined: 08 August 2005

### r3c9

Hi. Sorry. But I am not sure how we can say for sure that r3c9 is 5 and not 9.
Thx.

Just trying to learn.
Paulie

Posts: 10
Joined: 08 August 2005

### Re: r3c9

Paulie wrote:Hi. Sorry. But I am not sure how we can say for sure that r3c9 is 5 and not 9.
Thx.

Just trying to learn.

After the naked pair, you have eliminated other digits in those two grids except '4' and '6'. Then '5' must be there because in column 9 there is only one '5' there.

Posts: 62
Joined: 15 July 2005

Thx. a lot. It seems so simple now!

Paulie

Posts: 10
Joined: 08 August 2005

Paulie wrote:Thx. a lot. It seems so simple now!