Comments on: Killer Sudoku Pro / All Signs

By: Gareth Moore

Gareth Moore — Fri, 04 Nov 2011 20:39:58 +0000

There are more of these in each issue of my Sudoku Xtra magazine – take a look at http://www.sudokuxtra.com.

There are also loads of other puzzles too, of course! (And not just Sudoku variants)

By: Jeanette Dyson

Jeanette Dyson — Tue, 11 Oct 2011 19:22:35 +0000

I love Killer Sudoku puzzles and at the weekend there was a Killer Sudoku Pro in The Telegraph. I have yet to attempt yours above but wonder if you have any more I can try. I only like the Killer types. Thanks for your time. These are fab !!! Jeanette )

By: Gareth Moore

Gareth Moore — Tue, 27 Apr 2010 21:58:39 +0000

The largest number DOES have to go first. It’s just that it doesn’t matter what order you write them in the grid. Pick the largest number from the cage and use that first, then subtract or divide by the other numbers in the cage.

Hope this helps!

By: Laine

Laine — Mon, 26 Apr 2010 17:18:39 +0000

Aha! Now I see I thought that as division & subtraction aren’t commutative, the larger number(s) had to go first, and this is the first puzzles I’ve done where my assumption hasn’t worked!

Live & learn
Thanks for your explanations, now let’s see if I can solve the rest of the puzzle…

By: Spittledung

Spittledung — Mon, 26 Apr 2010 13:35:16 +0000

I believe that you missed the point in my previous post…

The larger number does NOT have to be the first one in the 3- cage (the one on the left). So by your deductions above it IS possible to have “4 (on the left) and 7 (in the region which you are deducing)” or “3 (on the left) and 6 (in the region which you are deducing)”.

So it is possible to have either 4_7 or 3_6. Now continue solving….

By: Laine

Laine — Sun, 25 Apr 2010 16:55:16 +0000

Hi there Spittledung!
Can’t have 7-4 or 6-3 in the 3- cage, that would put the 4 or the 3 in the square and the 24x cage already has both 3 & 4 in it!
I’ve got so hooked on the “all signs” Sudoku

By: Spittledung

Spittledung — Sun, 18 Apr 2010 16:11:03 +0000

Minus signs are tricky in KenKen type puzzles…

It has been a while since I have done this puzzle, but the glitch in the logic above comes with the 3- cage. You say that the 7 can’t go into this cage, but it could be 7 and the other number being a 4 (7-4=3). Likewise the 6 might work with the other number being a 3 (6-3=3). Further solving needs to be done…

I believe the something you might be missing is that the digits can be in any order for subtraction cages so long as the bigger number minus the smaller number gives the result, For the 0- cage in the same region, the biggest number in the cage minus the other two combined give 0.

It is always great to see others commenting about puzzles. Please stick around Laine.

By: Laine

Laine — Sun, 18 Apr 2010 15:37:14 +0000

Am i missing something? Spittledung says it’s not hard, but look at the bottom RH box – it doesn’t work!
Single box 8 must contain 8
9x can only be 1×9 (3×3 is not allowed)
24x can only be 2×3x4 (anything else needs a 1 – already used for 9x – or uses a single digit twice)
10x can only be 2×5 and as 24x contains 2, the 2 of 10x must be in he middle bottom box and the 5 in the bottom right box
So now, in the bottom right box, we have 1,2,3,4,5,8,9, and we have 2 empty boxes – where to place the 6 & 7?
The 7 can’t go in the 3- box because that would require a 10 from which to deduct 7 to get 3. So the 6 has to go in the 3- box … but wait a minute, that means the other digit has to be 9: 9-6=3 right? But there is already a 9 in the bottom row….
Or, as I said, am I missing something?

By: Spittledung

Spittledung — Sun, 10 May 2009 06:57:05 +0000

Nice change. Not hard. Division cages feel as if they will be very easy to deduce since the dividend can’t be above 9 in value.

I would call this puzzle “MathDoku”. In the case of generating more interest, that would be like calling sushi “Cold Raw Fish” since many hear the word maths and flee. … but I still like the name.