## Missin logic in this hard/medium Sudoku from Su-Doku Time?

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

### Missin logic in this hard/medium Sudoku from Su-Doku Time?

Hey all of out there.

I tried this Sudoku from Su-Doku Time and got stuck. (Original grid on the left, the point I got to on the right)
An online solver I found (http://www.sudoku-lobby.de/sudoku-loesung/sudoku.sudoku?IDraster=482745) suggests to fill in a 7 in the first row fourth cell by the logic of trial and error - I don't like that.
So is there some logic solving method I am missing or is it only possible to go on by trial and error?

Sudoku 26.9.13.jpg (74.87 KiB) Viewed 550 times

Q
Quitschi

Posts: 1
Joined: 26 September 2013

### Re: Missin logic in this hard/medium Sudoku from Su-Doku Tim

You can continue from there using locked candidates, and naked pairs/triples. There is no need for either guessing or trial and error.

JasonLion
2017 Supporter

Posts: 640
Joined: 25 October 2007
Location: Silver Spring, MD, USA

### Re: Missin logic in this hard/medium Sudoku from Su-Doku Tim

Code: Select all
` *-----------* |...|...|..6| |..2|.8.|.3.| |..9|6.4|...| |---+---+---| |...|.5.|68.| |..5|.71|2..| |14.|...|..7| |---+---+---| |3..|..7|...| |71.|..8|...| |9..|...|.5.| *-----------* *-----------------------------------------------------------* | 458   378   1     | 237   23    59    | 489   27    6     | | 456   67    2     | 17    8     59    | 149   3     459   | | 58    378   9     | 6     123   4     | 18    127   258   | |-------------------+-------------------+-------------------| | 2     9     7     | 4     5     3     | 6     8     1     | | 68    68    5     | 9     7     1     | 2     4     3     | | 1     4     3     | 8     6     2     | 5     9     7     | |-------------------+-------------------+-------------------| | 3     5     468   | 12    1249  7     | 1489  126   2489  | | 7     1     46    | 5     249   8     | 3     26    249   | | 9     2     48    | 13    134   6     | 7     5     48    | *-----------------------------------------------------------*In row 9 there is a pair of 48 (all other cells in r9 cannot contain a 4 or 8r9c5 can drop the 4 making it a 13This makes a 13 pair in block 8 (middle bottom).The 1 can be removed from r7c4 allowing it to be set as a 2Now can you find a triple in row 1?`
dan

ArkieTech

Posts: 2956
Joined: 29 May 2006
Location: NW Arkansas USA

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

it's a 2-move puzzle

b2 "naked" duo --> r1 trio

Pat

Posts: 3641
Joined: 18 July 2005