# Posts tagged Killer Sudoku

## Product Killer Sudoku

Mar 21st

Product Killer Sudoku 9×9 puzzle

If you’re interested in sudoku, come along to the official UK sudoku championship next weekend, the 29th-30th of March, at Selsdon Park Hotel just south of London, outside Croydon. There’s full details on the UK Puzzle Association site. There’s still spaces available.

Mind you, it’s not just sudoku – there’s also the UK puzzle championship taking place the same weekend, and there’s a low price which includes overnight accommodation and most meals for those who take part. Winners of both events get the chance to represent the UK in the World Puzzle Championships and World Sudoku Championships.

One of the puzzles in the sudoku part of the tournament is Product Killer Sudoku, a variant on Killer Sudoku where multiplication, rather than addition, is used.

So: just place 1 to 9 once each into every row, column and bold-lined box. Also place numbers in each dash-lined cage so they multiply to the given total. You also can’t repeat a number within a dashed-line cage.

## iPad, iPhone and other touch support on PuzzleMix

Sep 28th

Just a quick heads-up that PuzzleMix, my site where you can play a wide range of puzzles online, now supports touch screen play for all of the number entry puzzles – so that’s Sudoku, Killer Sudoku, Futoshiki, Calcudoku, Skyscraper, Sudoku X, Kropki Sudoku, Killer Sudoku Pro, Jigsaw Sudoku, Consecutive Sudoku, Wraparound Sudoku, Sudoku XV, Killer Sudoku X, Odd Pair Sudoku and more.

It’s pretty darn awesome, even if I do say so myself! It handles the screen touch events directly so it’s just as fast as running a native application on the iPad or iPhone. It also works on other devices.

## Killer Sudoku Zero

Jun 20th

Zero Killer Sudoku 9×9 1 puzzleProbably because it sounded cool, or it was invented by someone who didn’t quite speak English, Killer Sudoku puzzles with some of the redundant clues removed are often referred to as ‘Zero’ Killer Sudoku. Or perhaps it’s because there are “zero redundant clues”. In any case, here’s one of those puzzles, where I have taken out all but the clues you definitely need to get a unique solution.

Usual Killer Sudoku rules apply: Place 1 to 9 in each row, column and bold-lined box as usual, but you must also ensure that each dashed-line cage adds up to the total given at the top-left of it. Numbers can **not** repeat in a dashed-line cage.

Speaking for myself, I found this puzzle really challenging to solve, but I can promise you that there’s no need to guess or use trial and error in any way – every deduction can be made using standard killer solving techniques.

Good luck!

## Frame Sudoku

Jun 7th

Frame Sudoku 9×9 1 puzzleHere’s a Frame Sudoku puzzle. Each number outside the grid gives the sum of the three nearest digits in that row or column, so for example if there is a 7 outside the grid then there must be a 1, 2 and 4 (1+2+4=7) in the first three cells in that row or column.

Regular Sudoku rules also apply – place 1 to 9 once each in all rows, columns and bold-lined boxes.

The actual logic in this is not especially tricky, but I certainly found it took me quite a while to test solve it (20 minutes or so, although I was watching TV…) – I’d be interested to know how long it takes you to solve it too!

## Killer Sudoku

Oct 14th

Sudoku Xtra 11 is out now, but I’m holding off the announcement post until it’s available on Amazon.com too. In the mean time, here’s a Killer Sudoku puzzle.

Just place 1 to 9 in each row, column and bold-lined box. Each dashed-line cage should add to the given sum, and you can’t repeat a number in a cage.

## Samurai Killer Plus and Minus

May 14th

Killer Plus Minus Samurai puzzle

If you’re a Sudoku Xtra reader you’ll have seen these in their regular 9×9 form in both issues 5 and 6, but this is the first time I’ve made a Samurai one, and the first time I’ve posted one here I think.

This is essentially a regular Killer Sudoku puzzle, *except* that instead of placing 1 to 9 you must place -4, -3, -2, -1, 0, 1, 2, 3 and 4 into each row, column and bold-lined 3×3 box. There are also two overlapping 9×9 grids to solve simultaneously.

As in regular Killer, the values in each dashed-line cage must sum to the given total, and you cannot repeat the same number within any one cage.

Good luck!

## Samurai Killer Sudoku Pro 6×6

Apr 27th

Killer Sudoku Pro 6×6 Samurai puzzle

It’s been quiet here recently – much of my effort has been going on my UK General Election site, *How To Vote**, *although Sudoku Xtra 6 was out on Saturday too. Anyway, there are still 10 days to go to the election but after that I’ll get some time back!

However I thought I should finally post another puzzle – so here one is. Place 1 to 6 in each row, column and 2×3 box (rows and columns are defined by the three underlying 6×6 grids, which you have to infer from the stepping). Also place numbers so that the value at the top-left of each dashed-line cage results from applying the operation between all the value in that cage. For subtraction and division start with the largest value.

Have fun!

## Toroidal Killer Toroidal Jigsaw Sudoku

Mar 19th

Toroidal Killer Jigsaw Toroidal puzzle

A while back someone asked for some variant toroidal patterns on PuzzleMix, so I was just adding a couple of them to the daily puzzles section when it occurred to me that I could put up a few toroidal killer sudoku too, for a change. However I then realised that the code which creates the HTML will need editing to cope with toroidal regions, but I knew my PDF code was more flexible… and then I thought it would be great to mix this with some toroidal jigsaw regions too… and here’s the somewhat confusing result! A Toroidal Killer with Toroidal Jigsaw regions.

Now if you enjoy this twisted beast let me know, otherwise I probably won’t make any more of them!

Full rules:

- Place 1 to 9 in each row, column and bold-lined jigsaw region
- Place numbers so that the dashed-line cages add to the total given
- No number can repeat in a dashed-line cage.
- Some jigsaw regions and cages ‘wrap around’ the outside the puzzle, continuing at the start/end of the same row/column

Good luck!

## Killer Sudoku-X

Mar 4th

I wrote quite a lot yesterday about whether you “needed” the X in some Sudoku-X puzzles. I promised that I’d follow up with the result of analysing a stack of Killer Sudoku-X puzzles, and so here is that result.

I picked 64 Killer Sudoku-X puzzles (52 for the daily puzzlemix section plus 12 for the weekly puzzlemix section), and of those about 5 or 6 (I didn’t write it down…) could be solved via reasonable logical deduction *without* using the ‘X’ diagonals. So that’s roughly 10% of puzzles, if picked at random, that don’t need it. Quite a bit worse than regular Sudoku-X (see previous post), but nowhere near as high a percentage as I’d expected – I had thought it could be 50% or more, although I should say that this isn’t actually a fair comparison because I disabled the cleverest maths-solving techniques from my analysis software. So in fact this is comparing clever Sudoku-X solving against the same Sudoku-X solving with the addition of relatively less clever Killer Sudoku-X solving, so perhaps this biased the result much more to the non-Killer result (from yesterday) than it should have done. But anyway, I’m not writing a scientific paper and it’s good enough for me!

Killer Sudoku-X puzzleSo the result of all this is pretty simple: the Killer Sudoku-X on PuzzleMix for the coming year should be better than ever! You should need that X every time…

PS Enjoy the Killer Sudoku-X I’ve attached here! Just place 1 to 9 in each row, column, 3×3 box and main diagonal, plus make sure the cages add to the given amounts – and don’t repeat a number in a cage.

## Jigsaw Killer Sudoku

Mar 2nd

I’ve recently been working on refreshing the content for PuzzleMix.com, my play-online puzzle site, and one of the puzzle types I’ve been making is Killer Jigsaw Sudoku, where you not only have the jigsaw-shaped Killer regions but also jigsaw shapes instead of the regular 3×3 Sudoku boxes.

So I thought it would be a good idea to post one of these puzzles here – they can be quite tricky, at least until you get your head around the difference between these and regular Killer!

The rules are simple:

- Place 1 to 9 in each row, column and bold-lined region
- Place numbers in the dashed-line cages that add up to the given total for that cage
**No number can be repeated**in a dashed-line cage

Good luck!

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