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akif · Guest

I was stuck in the Sept 17 puzzle at the following point

6xx 172 x9x
x9x x36 125
2xx 9xx 7xx

x4x xx1 x8x
5xx xxx xx1
x2x 6xx x4x

xx2 3x8 xxx
463 x1x x7x
x8x 7xx xx3

Then I draw the puzzle on DailySudoku site and asked for hint. The hint given was R5C2 = 7. I am not able to understand the logic behind this clue.

Can anyone help me and explain the technique used here ???

geoff h · Joined: 07 Aug 2005 Posts: 58 Location: Sydney

Hi there,

You must first consider Column 1. Nr 3 can not appear in row 2, row 7 or row 9. Therefore, Nr 3 MUST be in ither r4c1 or r5c1. Therefore, all other 3s can be deleted as possibilities in Box No. 4 ( r4c1 - r6c3). R5C2 only has the possibilities of 3 and 7. Therefore you can delete Nr 3 from r5c2 and leave the Nr 7.

Hope this helps.

Cheers.

Guest · Posted: Mon Sep 19, 2005 11:24 am Post subject:

Guest · Posted: Mon Sep 19, 2005 11:45 am Post subject:

Sorry, I made a small typo!! Let's just still consider Column 1. As I said, 3 can not appear in either Row 2,7 or 9 as 3 is already in each of those rows ( r2c5, r7c4 and r9c9 ). Therefore the Nr 3 MUST be in either r4c1 or r6c1 - sorry, I previously said r5c1 which was my typo!!

This then means that Nr 3 can not appear anywhere else in Box No. 4 as it HAS to be in either r4c1 or r6c1.

Does this help clarify??

Guest · Posted: Mon Sep 19, 2005 12:20 pm Post subject:

Yup, the 7 is visible now Smile

Puzzle solved 15 mins later. Thx!