dailysudoku.com

[OhioSaba]

I was told about this site earlier today, so after working today's "hard" puzzle I decided to go back and look at the archives. When I saw Sunday's "very hard" puzzle I got started immediately.

Long story short - I got stuck. When I looked at the discussion it looked like others had gotten further before they got stuck, so I started using the "solver" to try and move past where I was. I do not understand why a 6 is placed where the # is below. At this point in the solution it seems to me that a 6 could also be placed in either of the *s.

--2 --- 198
-4- -9- -36
3-- --- --4

--- -73 -4-
--- 1-6 ---
-8- 25- -1-

825 --- *#3
937 -2- *51
164 --- 9--

I would greatly appreciate it if someone could nudge me toward a better understanding.

Thanks

[fabfourfanfromohio]

Here's the logic:

--2 --- 198
-4- -9- -36
3-- --- --4

--- -73 -4-
--- 1-6 ---
-8- 25- -1-

825 --- *#3
937 -2- *51
164 --- 9--

Using standard notation, Columns are numbered 1-9 from left to right.
Rows are numbered 1-9 from top to bottom. Cells are identified by row, column: 2,1 is the cell in row 2, column 1.
Square's are numbered:
123
456
789

Column 8 must have a 6. It can't be in square 3 because it already has a 6. It can't be in row five because it has a 6 in cell 5,6. And finally, it can't be in row 9 because there's a 6 in cell 9,2. Therefore, the only cell left in column 8 that can be a six is cell 7,8.

Hope this makes sense.

[OhioSaba]

This makes perfect sense. I had not considered that type of approach. Thank you for providing me with a new technique.