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

I cannot work out this Sudoku. Can any body help me with it (with analysing process)? Thanks!

• • 2 | • 5 • | 7 • •
• • • | 8 3 9 | • • •
6 • • | 2 • 1 | • • 3
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• • 1 | • • • | 6 • •
8 6 • | • • • | • 5 7
• • 5 | • • • | 3 • •
----------------------------------
5 • • | 1 • 6 | • • 4
• • • | 7 4 8 | • • •
• • 6 | • 2 • | 9 • •
maria129129

Posts: 1
Joined: 14 April 2017

Right off there are three cells that can only contain a single possible digit.

When I solved this puzzle I used singles, locked candidates, a Unique Rectangle, a Hidden Pair, and a Naked Pair. There are other paths to solving the puzzle, but all of them require at least one mid-level technique (not necessarily the Unique Rectangle I used, but something more complex than Pairs).

JasonLion
2017 Supporter

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

One can even get by without any advanced method. After each naked single, be sure to remove all the numbers that can "see" the new solved number.
Naked single: r1c6 must be 4
Naked single: r3c5 must be 7
Naked single: r7c5 must be 9
Naked single: r1c4 must be 6
Naked single: r4c5 must be 8
Naked single: r5c5 must be 1
Naked single: r6c5 must be 6

3s at r9c46 only ones in box => -3 r9c128.

5s at r8c79 only ones in row => -5 r9c9.

Naked triplets of 249 at r4c89, r5c7 => -2 r6c89, -4 r6c8, -9 r6c89

9s at r4c89 only ones in box => -9 r4c124.

Naked pairs of 18 at r69c9 => -1 r128c9, -8 r1c9

Naked single: r4c9 must be 2
Naked single: r5c7 must be 4
Naked single: r4c8 must be 9
Hidden single: r5c6 must be 2
Naked single: r6c6 must be 7

4s at r23c3 only ones in column => -4 r2c12, r3c2.

Naked pairs of 18 at r16c8 => -1 r289c8, -8 r379c8

Then singles to the end

Phil
pjb
2014 Supporter

Posts: 2025
Joined: 11 September 2011
Location: Sydney, Australia

Code: Select all
`..2.5.7.....839...6..2.1..3..1...6..86.....57..5...3..5..1.6..4...748.....6.2.9..`

Seven Naked Singles:
- 4 @ r1c6
- 6 @ r1c4
- 7 @ r3c5
- 9 @ r7c5
- 8 @ r4c5
- 1 @ r5c5
- 6 @ r6c5

One Hidden pair:
- 18 @ r6c89

One Naked pair:
- 35 @ r9c46

One Hidden pair
- 56 @ r28c9

One Hidden single:
- 2 @ r4c9

Two Naked singles:
- 4 @ r5c7
- 9 @ r4c8

Two Hidden singles:
- 9 @ r1c9
- 2 @ r5c6

One Naked single:
- 7 @ r6c6

One Hidden pair:
- 29 @ r68c1

One Naked pair:
- 39 @ r28c3

Rest Naked and Hidden singles to the end.

R. Jamil
rjamil

Posts: 253
Joined: 15 October 2014
Location: Karachi, Pakistan