dailysudoku.com

[BrendaS]

I am stuck at the following:

XX2 479 6XX
647 85X X9X
X9X 61X 4X7

874 XX1 569
253 986 714
961 547 832

7XX XX8 X4X
X3X XX4 X7X
4X6 795 3XX

Can someone help?

Thanks,
Brenda

[Steve R]

Hi, Brenda

The only places for 5 and 6 in box 9 are r7c9 and r8c9. This means that the 8 in box 9 occupies row 9.

Taking account of this, there is only one place for 8 in row 8.

Steve

[BrendaS]

Thanks Steve,

It looks so obvious now.

Brenda S.

[jabejochke]

Sarah and others,

Steve’s insight and/or approach I don’t have. He makes it so obvious.

I recognized it differently. In processing box 9, I saw a 56 hidden subset in c9 at r7c9 and r8c9 which contained candidates <1,5,6,8> and <1,5,6,8> thereby eliminating the ‘1’s’ and ‘8’s’ in those cells hence:

Ø creating paired ‘8’s’ in box 9 at r9c8 and r9c9, which in turn
Ø eliminated the other ‘8’ in row 9 at box 7 – r9c2 – which
Ø meant that the only ‘8’ in box 7 must be at r8c3

Again, I wish I had Steve’s insight – it would be a lot faster. As importantly, his response gave me a totally new way to think about and look for ‘hidden subsets’.

Jack

[TKiel]

Jack,

I think you recognize it the same way, you merely describe it in a different manner.