dailysudoku.com

[el_sapo]

Code:

-8- -67 --- X4- --3 8-6 69- 8-- --2 8-2 6-- 4-- 539 -7- 618 4-6 -8- 92- 7-4 --8 -69 --8 7-- -34 --- 54- -8-

I'm stuck here... the draw program says that there should be a 2 in slot X.. can anyone explain me why??[/img][/url][/list][/code]

[curiousgeorge]

Looks to me like the X should be a 1 (unless one of us has copied the table down wrong).

To start, I'd say that X can be 1 or 2.

Looking across the top row:
R1C1 can be 1,2,3
R1C3 can be 1,3,5
R1C4 can be 1,2,4,9
R1C7 can be 1,3
R1C8 can be 4,5,9
R1C9 can be 1,5

Since R1C3, R1C7, and R1C9 can be only 1,3, or 5, we can eliminate 1,3,5 from the rest of R1.

Thus R1C1 must be 2.
And so R2C1 (the X you were trying to solve) must be 1.