What is the best variant of Sudoku

6 simple tricks that are guaranteed to solve any Sudoku

Have you ever heard of solution methods such as jelly fish, sword fish with fin or X-wing? Forget it! Here are six very simple methods by the Sudoku master Stefan Heine, with which you can get very far and are guaranteed to solve all Sudokus. There are simple and proven methods that crack even the most difficult Sudokus.

Stefan Heine regularly supplies the German Sudoku Championship and Sudoku World Championships. On our website you will also find three new Sudokus by Stefan Heine every day in the difficulty levels easy, medium and difficult.

You will find out in this article:

  1. Trick: Find a number in the 3x3 block
  2. Trick: Find a number in a column or row
  3. Trick: Find a number in a single box
  4. Trick: Find a number in the entire Sudoku puzzle
  5. Trick: Use the exclusion procedure by means of reference numbers
  6. Trick: Find a number at the intersection
  7. About Stefan Heine

1 Find a number in the 3x3 block (M1)

This is the easiest way to get a number - you know it. Look for the 8 in the upper left 3x3 block (left in Sudoku).
The fields with the dark blue arrows are out of the question because of the 8's in the same column or row: All that remains is the field M1 - this is where an 8 comes in.

Solution: M1 = 8

2 Find a number in a column or row (M2)

This method is just as easy. Find a number in a column or row. In the example (Sudoku above) the 5 is missing in line X. The dotted arrows show you where no 5 can go. There is only one space left: M2 - this is where a 5 goes!

3 Find a number in a single box (M3)

It's actually quite easy, but many have never tried it. Count a single box through to find a number. Look at the arrows around the field M3 (in the Sudoku above). All numbers touched may not be in this field. The following are touched: 1, 2, 3, 4, 5, 6, 7 and 8. What other option than to enter 9 in M3?

4 Find a number in the entire Sudoku puzzle

An 8 is wanted! If there are only two or three boxes left in a 3x3 block for a number you are looking for and they are next to or on top of each other, this can often be of great help. At the top left the 8 is still missing and in the middle right 3x3 field there are only two boxes left for it.

In the corresponding rows and columns, the 8 cannot appear anywhere else than in these two fields. If we now look into the 3x3 block at the top right, there is only one possible place where the searched number can still go - you have found an 8 (M4).

Solution: M4 = 8

5 Use the exclusion procedure by means of reference numbers

Two digits can jointly block two empty fields of a 3x3 block for other digits, even if it is not yet clear which digit will be where at the end.

In our example this applies to the 2 and the 6 in the lower right 3x3 block. Both digits are already in row X and in column Y. That is why both the 2 and the 6 must be in one of the two fields in row Z. We have temporarily entered both digits together as reference digits, because another digit is no longer possible for these two fields.

If you now look again at column Y and line X, you can see that the 4 must be entered in field M5, because it is already in the bottom line. As a result, she can no longer enter the fields to the right and left of the 5 in line X.

Solution: M5 = 4

6 Find a number at the intersection

We're looking for the 3 in the middle 3x3 block. Try it yourself! If we look at row "X" with method 2, only three fields remain in the middle 3x3 block for the 3 we are looking for, because the two empty fields in the blocks on the right and left are blocked by 3s in the corresponding columns (see vertical arrows ).
The same applies if you look at the “Y” column. There, too, only fields remain in the middle 3x3 block for the 3, because the two empty fields in the lower block are blocked by 3s in the crossing lines (horizontal arrows).

For the 3 in the middle 3x3 block, only the fields that are marked light blue in the example remain. In such an area, the number must then always be entered in the intersection point (M6).

Solution: M6 = 3

About Stefan Heine

There aren't many professional puzzlers, especially not Sudoku specialists like Stefan Heine. He turned his passion into a job. Even as a child, he preferred tinkering to bedtime stories. Today, in addition to the classic Sudoku, his successful puzzle maker has another 120 variants of the popular number puzzle on offer. The puzzles he invented are printed over 400 million times a month - in magazines, newspapers and books.

Stefan Heine has been publishing Sudoku books since 2006 and is now giving them 50-volume book series "Heine's Rätselbibliothek" out. Take a look - we hope you enjoy solving the tricky puzzles!

Stefan Heine: Sudoku difficult to extreme 4. ISBN: 978-3-939940-37-1. Verlag Presse Service, 9.95 euros

Click here to go to Stefan Heine's website