killer su doku

[psych25md]

Thanks to the Times...

This probably sounds silly seeing as i am such an addict to regular sudokus but i can NOT seem to start anything past the gentle killers! how do you start it without any single sum boxes (the one where only one number can go in, the freebie!) even with "6"s, how do you know where to put the 1,2,and 3? Its driving me mad! Please help!!

[headhunter]

psych25md - I totally agree. I can't seem to get across the jump from the pretty straightforward gentle killers (which I would say are easier than a typical fiendish sudoku) to the moderate killer puzzle. I've put this on another thread on this site, but if anyone has any tips, they'd be very welcome.

[polly123]

Is there one of these on line so I can have a look? Am a bit of aSudoko fanatic and have recently found a 20x20 but too scared to start it lol!

Susan

[mrs p]

Yes, they are difficult, aren't they! I am struggling to do the moderate ones, but have discovered that it helps if you look for the cells all in one square - not turning a corner and spread between 2 squares. So if you get 3 in a row in one square totalling, say, 24, the only possible options are 7+8+9; so those numbers won't be in the rest of the row or column.   With 3 cells totalling 14, if one of them is definitely 6, the other 2 can only be a combination of 3+5 or 1+7 otherwise you repeat the number ...  I also find it helpful to work out where the 1 or the 9 can't possibly be. Good luck.

[sudokuaddict]

I managed to solve a tough one of these yesterday.  I had to seek out pairs of boxes totalling 17 which can only be 9+8, 16 which can only be 9+7, 15 which can only be 9+6 or 7+8 and 14 which can only be 9+5 or 8+6.  

You can also get clues from inner boxes where the cells are all inside on box or in a straight line - any 5 cell inner box totalling 15 must contain all digits from 1 to 5, a 4 cell inner box totalling 10 must contain all digits from 1 to 4 etc etc.

You also need to use the fact that the digits from 1 to 9 add up to 45 (very useful where most of the cells in a box are contained within inner boxes entirely bounded by the box).  For example a box contains 2 complete inner boxes of 3 cells each totalling 15. A third inner box of 4 cells (one cell in a neighbouring box) totals 16.  The 10 cells add up to 46, therefore the one cell in the neighbouring box must be a 1.  This example can be seen in The Times published 31/8/05 (tough, 40 mins).

Hope this makes some sense......