dailysudoku.com

Nenthorn · Joined: 13 Nov 2005 Posts: 11 Location: Scotland

I've been sailing through these very hards quite the thing - but now I'm brought back to earth. I cannot for the life of me see what I'm missing here. Can one of you geniuses help me, please?

Here's where I am . . .

900 078 020
010 360 400
300 050 000
080 631 000
001 085 600
600 047 010
100 890 007
804 710 090
769 520 001

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

Hi Nenthorn,

I'm not sure what values you have as possibilities in the missing squares, but as you appear to know what you are doping , I will assume that you have done basic things such as identifying hidden pairs and unique numbers.

What you can firstly do is consider Row 4. As you can see, the only possibilities for Nr.9 in Row 4 are in cells r4c7 and r4c9. Therefore, you can remove Nr.9 from all other cells in Box No. 6 (cell nos. r4c7 - r6c9).
This is particularly meaningful for cell r6c7 as the remaining possibilities for this cell are then 2,3,5,8.

Now, have a close look at Column 7. There is now a naked quadruplet of 2,3,5,8 in cells r6c7, r7c7, r8c7 and r9c7. This means you can delete these numbers from all other cells in Column 7. This then easily leads to placing the Nr.1 in cell r1c7 and then the Nr.4 in cell r1c4 and the Nr.5 in cell r1c2.

You should be okay from there.

Hope this helps.

Cheers.

Nenthorn · Joined: 13 Nov 2005 Posts: 11 Location: Scotland

Thanks Geoff. I had been staring so hard looking for hidden things I couldn't see the naked one! You're a mate.

daykart · Joined: 22 Nov 2005 Posts: 10

Listen Mr. Smartypants (geoff h),

I would like to echo Nenthorn's sentiments about this puzzle. I too have been going through them like a razor..I only do the very hard ones...but this one "stumpttteddd" me.

Now you come along and in a casual no nonsense sentence say "naked quad" col. 7....I have been looking at this puzzle for hours!!!!!

Thanks buddy...now I can sleep tonight...after I bang my head into brick wall to punish myself for stupidity.

Thanks again

daykart

dotdot · Joined: 07 Dec 2005 Posts: 29 Location: oberseen

Hallo daykart

I would never see the quad either,
but maybe you would have a better chance at seeing the (complementary) pair instead?

David Bryant · Joined: 29 Jul 2005 Posts: 559 Location: Denver, Colorado

Here's another way to get past the spot Nenthorn illustrated.