## Fiendish 16/6/05

Post the puzzle or solving technique that's causing you trouble and someone will help

### Fiendish 16/6/05

I think there are 2 solutions to this one. I used my usual technique of only filling in boxes where there was only 1 candidate digit. This got me to the following situation:

74* 1** 8**
*** 78* *4*
*** 4*5 *17

*9* 248 735
238 957 461
574 613 928

*6* 37* ***
**7 *6* ***
3*2 *91 674

At this point, I ran out of obvious options, so for whatever reason I stuck a 6 in R1C9 and proceeded to solve it. However, on putting this scenario into an Excel solver I am working on, it looks like I could have put the 6 in R2C9 too, and still got a unique solution.

These are the 2 solutions:

743 129 856 745 126 893
125 786 349 123 789 546
986 435 217 986 435 217

691 248 735 691 248 735
238 957 461 238 957 461
574 613 928 574 613 928

869 374 582 869 374 152
417 862 593 417 562 389
352 891 674 352 891 674

I thought the Times Sudoku only had 1 solution, or have I missed something?

BTW, the Excel solver is an exercise to get my rusty programming brain working !
nobbyclark

Posts: 3
Joined: 17 June 2005

Take a really good look at row 7/box7/column 4. All three of these have the numer 8 twice. Which is incorrect.

The move you are looking for is the 1 in r2c1.

What are the candidates for r2c1?
Where can the number 6 go in boxes 2 and 3? what does this mean for box 1?
Where can the number 9 go in boxes 2 and 3? what does this mean for box 1?

Now fill it in.
Animator

Posts: 469
Joined: 08 April 2005

Cheers - spotted it now.

I would appreciate your thinking on why the 1 must go in R2C1 - I can see that it does, but am not sure why: at the point I got stuck, R2C1 could contain 1, 6 or 9. 6 and 9 could also be in R2C3, R2C6 or R2C9 or R3C1. What is the reason that this leaves 1 as the only option for R2C1. Thanks.
nobbyclark

Posts: 3
Joined: 17 June 2005

Answer my second and thrid question.

Here are two new question, which mean exactly the same:

Where can the number 6 go in row 3? (what box is that, and what does it mean for that box?)
Where can the number 9 go in row 3?
Animator

Posts: 469
Joined: 08 April 2005

Thanks, I get it now.
nobbyclark

Posts: 3
Joined: 17 June 2005

An alternative view which I used is to consider where the numbers 2 and 3 can go in row 3.
Does this give something useful, eg a pair?
Does this allow you to eliminate possibilities in box 1?
SteveF

Posts: 86
Joined: 26 March 2005