I most basic strategy to find missing numbers is scanning and it consists of

1)Cross-hatching.

2)Counting.

1) Crosshatching (shown in the first picture). You scan rows and columns to eliminate where a specific number can be in a given region.As you can see there is only one legal place left for the 1(marked green).

2)Counting. In counting you simply count all the different numbers that's in a row,column and region that connects to one cell. if there is just one number missing then thats what should be in the cell. Take a look at the second picture and see if you can figure out the missing number in the green cell.

the correct answer is :4

legend: green = result

red = cause(the cause of the result that is)

1)Cross-hatching.

2)Counting.

1) Crosshatching (shown in the first picture). You scan rows and columns to eliminate where a specific number can be in a given region.As you can see there is only one legal place left for the 1(marked green).

2)Counting. In counting you simply count all the different numbers that's in a row,column and region that connects to one cell. if there is just one number missing then thats what should be in the cell. Take a look at the second picture and see if you can figure out the missing number in the green cell.

the correct answer is :4

legend: green = result

red = cause(the cause of the result that is)

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The best method is to use google goggles app and it'd solve it for you in like 2-3 seconds XD

Great instructable! For beginners with iPhones i recommend the Sudoku app from Pennypop. It makes sudoku so easy to learn, looks gorgeous, and it's totally free.

Nice instructable! I was thinking about writing up something like this, but am about as far from a mathematician as one can get, so I never really got around to it. I call my "rules" the "Two of a Kind" (two of the same number, in adjacent columns/rows that narrow down the placement in the third row of that set of horizontal or vertical blocks), two pair (two pairs in a row, column, or a block, eliminate all numbers in that associated row/column and/or block....three triples is the same, but with three numbers, and I find it more difficult to use this rule, and it shows up a whole lot less, I find; besides, the other rules usually trump the 3-Trips), and "Three-Pack" (all three numbers in a row/column within a block are filled in, this allows placement of single numbers of adjacent rows to be placed in the other two blocks in that row/column of blocks). I find that, with a minimum of WAG's (Wild @rsed Guess), I can usually plow through the hardest level of the Sudoku app on my Droid3 in about 15-20 minutes.

Sudoku is a fun game to get into. all the different <a href="http://sudokustrategies.net" rel="nofollow">Sudoku Strategies</a> can really work the brain. a great past time<br />

I am a beginner at this little brain-tease, and have discovered a solution that will save the masses from the madness of that one grid that cannot be solved; take a black marker and change things to suit yourself.

hehe

Wasn't this instuctable done already? They also suggested the same method

They just seggested scanning,not candidat elimination nor the xy wing

WRT: Step 5
I understand the logic of the numbers but not what you were saying about "x,y,z". Did you miss something out?
Cheers,
Pat. Pending

the xyz is only to show where the name came from