The New Sudoku Players' Forum

[JFistere]

This is "Challenging" puzzle #171 in The Big Book of SoDuKo #1 by Mark Huckvale, Newmarket Press. I have gotten this far:

. 2 4|9 . 3|5 . .
. 7 .|4 1 5|2 . .
3 1 5|7 . 2|. . 9
-----+-----+-----
7 8 .|6 4 .|3 . 5
. 5 .|3 7 .|. . 8
. 4 3|5 2 8|. 6 .
-----+-----+-----
4 9 7|8 3 6|1 5 2
2 6 8|1 5 7|. . .
5 3 1|2 9 4|. . .

I resorted to a program called SoDuKo solver and it tells me that the next number is a 4 that goes in Row 8, Column 9 (under the 2). For the life of me, I cannot figure out why. If that is not the correct number, what would you suggest?

Thanks,
John Fistere

[JFistere]

Oops, I have just realized that this should have gone in the non-Papacomm forum, and I have reposted it there.

John Fistere

[emm]

Check column 9. Is there any other cell the 4 could go into? If not then it must go there. It's harder to see because it's not the only number that could there, but if it's the only place for that number then it must be the one. It's called a hidden single.

PS : Me too - reposted that is, not hidden single!