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Hidden Pairs can be found easily using pencil marks. Take a look at the sudoku: After a few singles pencil marks were applied for candidates 4 and 8. The Hidden Pair in r3c46 becomes immediately visible. No other candidate can go into one of those cells.
Hint: Hidden Quads only appear in houses with seven or more unsolved cells. The puzzle above has only two blocks, two rows, and three columns that meet that requirement.
What is a hidden cell in Sudoku?
If two candidates can be found in only the same two Cells of a region (Row, Column or Square), then one of these candidates is the solution for one of these Cells and the other candidate is the solution for the other Cell. Hence all other candidates can be deleted from these two Cells.
Is there a strategy to solving Sudoku?
The most basic strategy to solve a Sudoku puzzle is to first write down, in each empty cell, all possible entries that will not contradict the One Rule with respect to the given cells. One more complicated strategy is to look at pairs or triples of cells within a row, column, or block.
Can Sudoku always be solved without guessing?
Sudoku does not require guessing. In fact, when solving Sudoku puzzles, you’re better off NOT guessing at all. Sudoku is a logic puzzle, using the power of simple deductive reasoning and process of elimination to fill in the gaps in the grid. Simply put – you don’t need luck to play Sudoku.
Why are there hidden triples and quads in Sudoku?
They are called “hidden” because there are other candidates in the same squares as the pairs, triples, and quads. A hidden pair occurs when a pair of numbers appears in exactly two squares in a row, column, or block, but those two numbers aren’t the only ones in their squares.
Are there any numbers that only appear in three cells in Sudoku?
The rule still fits. In fact, it gives us even more information later. The fact of the matter is that 2, 6, & 8, as a “set”, only appear in three cells. Three numbers; three cells.
Where are the pencil marks in a Sudoku 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… 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.
Where do you find 5 and 9 in Sudoku?
The 5 and 9 only occur in those two squares and nowhere else in the row, so those two squares can only contain 5 and 9 and no other numbers. Because of that, you can get rid of the other candidates in those squares, as shown crossed out in red.