Note all possible figures for each cell. Jott them down in a small font, in the righthand side of the cell.

4 1 5
7 8 3
2
9		 2 6
9		 2
6
7 8 2
4 9 6
1 3 5
3 6 9
1 2 5
4 7 8
2 5
8		 2
5		 2
8
1 3 9
6 4 7
3 1 4
5 6 7
8 2 9
6 9 7
8 4 2
5 1 3
3 5 4
2 5
8 9		 2 5
6 9		 2 6
8
2 6
8		 7 1
9 7 1
2
6		 4 3
8
2
6		 5 3
8
2 5
8		 6
7 3 5
8		 1
9 3
8		 4

 

Step 1 - Look for unique candidates

Then look in each row, column and ninesome for a unique candidate. When so, you are sure it must belong in that cell. Bingo!

You must remove this candidate you just filled in from the "adminstrations" in which it occurs: for each row, column and ninesomel. Because this process generates new information, repeat this method until no new candidates can be found.

After that, you proceed looking for patterns in the "administration".


Step 2 - Look for identical pairs

  The second pattern you look for, consists of equal pairs, duo's, ab en ab. For example:

2 6
8		 7 1
2
6		 5 3
8
9 3
8		 4

he first pattern you look for consists of two equal pairs, ab en ab. Whenever you find two cells in a column, a row or a ninesome with two of the same cadidates, you may remove these figures from the remaining administrations. (Both candidates must occurr of both cells - the one here, the other there, of reverse - and cannot occur elsewhere.) So the 8 must be expelled from the administration of the first cell in the row above:

2 6

 7 1
2
6		 5 3
8
9 3
8		 4


Stap 3 - Look for threesomes

The third pattern consists of three equal triples in three cells, abc, abc en abc. reat this pattern in the same way you treat two equal pairs, until you cannot remove any candidates anymore. 

hese are the remaining patterns:
- ab en ab (excludes ab elsewhere)
- abc, abc en abc (excludes abc elsewhere)
- abc, abc en ab (excludes abc elsewhere)
- abc, ab en bc (excludes abc elsewhere)
- ab, bc en ac (excludes abc elsewhere)

 

Stap 4 - Look for foursomes

In the same way you can us foursomes for your bookkeeping. Som frequently occurring quadruples, the all exclude abcd elswhere:

- abcd, bcd, bc en ab
- abcd, cd, bc en ab 
- acd, cd, bc en ab 
- ad, cd, bc en ab