#SUDOKU TRIPLES RULE FREE#

The puzzle above has only two blocks, two rows, and three columns that meet that requirement. Hint: Hidden Quads only appear in houses with seven or more unsolved cells. As I said, you can probably go your whole life without ever needing this technique.īut if you like a good challenge, here it is…

#SUDOKU TRIPLES RULE FREE#

Can you find it? If you can't, don't be discouraged! In fact, if this is discouraging you at all, feel free to scroll down and click 'Next', and you will not be any worse off for it. The puzzle below contains a 'Hidden Quad'. I'll just give you an example of one and leave it at that. It is quite possible that you will never even see one.įor this reason, I will not go too deeply into them. 35. No row, column, or 3×3 box can feature the same number twice. I should say, though, that these are extremely rare. In Sudoku, you must complete the grid so each row, column, and 3-by-3 box (in bold borders) contains every digit 1 through 9. Similar to Hidden Pairs & Triplets, a Hidden Quad is when you find four different pencil marks inside only four cells in the same house. And if you stopped here, you would still possess the skills to solve 95% of the Sudoku puzzles out there.įor the sake of being complete, there is one more technique I should mention real quick: Hidden Quads. Hidden Triplets are kind of hard, huh? Well, the good news is this is the hardest of the 'basic' techniques. The fact of the matter is that 2, 6, & 8, as a 'set', only appear in three cells. It's pretty simple and based on the fact that each 3×3 block, vertical column or horizontal row on Sudoku grid should contain numbers from 1 to 9 and each number can be used only once within 3×3 block, vertical column or horizontal row. In fact, it gives us even more information later. 'Last free cell' is the basic Sudoku solving technique.

You may have noticed that the '8' pencil mark only appears in two of the cells. Since 2, 6 & 8 are only possible in three cells, we can conclude that those three cells must be some combination of 2, 6, and 8! We can safely erase all the other pencil marks in them (erase the pink ones). Now, if we study very closely, we can see that the three cells indicated in green (below) are the only cells that contain the pencil marks 2, 6 & 8. A hidden triple is when you have the same three digits (or a subset of them) as candidates in exactly three cells within the same row, column, or block. In the example below, we see a block with only one cell solved and the rest of the cells pencil marked with all their possible candidates… As you may have guessed, Hidden Triplets work on the same concept as Hidden Pairs: When three given pencil marks appear in only three cells in any given row, column, or block, all other pencil marks may be removed from those cells.

Sudoku triples rule