Sudoku
Fill every row, column and box with the numbers 1 to 9 exactly once.
Fill every row, column and box with the numbers 1 to 9 exactly once.
Learn the rules of Sudoku and the solving techniques that crack every grid, then play the puzzle above.
Fill the 9x9 grid so that every row, every column and every 3x3 box contains the numbers 1 to 9 exactly once.
Every valid Sudoku has exactly one solution, and you never need to guess to find it.
Look for a cell where only one number can fit, or a number that can go in only one cell of a row, column or box. Filling these in opens up more.
When scanning stalls, note the possible numbers for each empty cell. Patterns among those candidates reveal the next moves.
If two cells in a unit can only hold the same two numbers, those numbers are locked to those cells and can be removed as candidates elsewhere in the unit.
Focus on rows, columns or boxes that are already nearly full. They give you the quickest certain placements.
Fill the 9x9 grid so every row, every column and every 3x3 box contains the numbers 1 to 9 exactly once, with no repeats in any row, column or box. A proper Sudoku has a single unique solution.
No. Every well-formed Sudoku can be solved by logic alone, with exactly one solution. If you feel you must guess, there is usually a placement you have missed by scanning rows, columns and boxes more carefully.
Scan for singles, cells where only one number fits, or numbers that can go in only one place within a row, column or box. Start with the most filled-in areas because they give the quickest certain placements.
A naked pair is two cells in the same row, column or box that can only contain the same two numbers. Those two numbers must occupy those two cells, so you can remove them as candidates from every other cell in that unit.