We hope you enjoy playing Sudoku online here for free! We have lots of options to help you play Sudoku, including undo/redo and the ability to
use pencil marks (placing multiple possible values on a square)! If you are logged in, you can even save your puzzle if you don't have time to finish it today.
SUDOKU GOAL 
•  Correctly fill in the missing elements of the Sudoku board to find the unique solution. 

SUDOKU PROCESS 
•  Click on an empty square of the Sudoku board to select it. 
•  Once a square is selected, the left, right, up, and down arrow keys may be used to select a different square. 
•  Click on an element in the list or press a key from 1 to 9 to modify the value in the selected square. 
•  To clear a value in a square, repeat the value that is in the selected square or click the empty square in the element list. 
•  To mark a value as a 'guess', click on the selected square. Click again to unmark it. 
•  Click the 'Edit Pencil Marks' checkbox or right click on a square to toggle the edit mode. (Pencil mark editing allows the player to enter potential values for the square without committing to a value.) 
•  To clear a pencil mark value, repeat the value of the pencil mark in the selected square. 
•  Once the Sudoku puzzle is solved, the player's score is incremented. 

SUDOKU CONSTRAINTS 
•  Every element must occur in each row exactly one time on the Sudoku board. 
•  Every element must occur in each column exactly one time on the Sudoku board. 
•  Every element must occur in each box exactly one time on the Sudoku board. 



SUDOKU GOAL 
•  Correctly fill in the missing elements of the Sudoku board to find the unique solution. 

SUDOKU PROCESS 
•  Click on an empty square of the Sudoku board to select it. 
•  Once a square is selected, the left, right, up, and down arrow keys may be used to select a different square. 
•  Click on an element in the list or press a key from 1 to 9 to modify the value in the selected square. 
•  To clear a value in a square, repeat the value that is in the selected square or click the empty square in the element list. 
•  To mark a value as a 'guess', click on the selected square. Click again to unmark it. 
•  Click the 'Edit Pencil Marks' checkbox or right click on a square to toggle the edit mode. (Pencil mark editing allows the player to enter potential values for the square without committing to a value.) 
•  To clear a pencil mark value, repeat the value of the pencil mark in the selected square. 
•  Once the Sudoku puzzle is solved, the player's score is incremented. 

SUDOKU CONSTRAINTS 
•  Every element must occur in each row exactly one time on the Sudoku board. 
•  Every element must occur in each column exactly one time on the Sudoku board. 
•  Every element must occur in each box exactly one time on the Sudoku board. 



SUDOKU GOAL 
•  Correctly fill in the missing elements of the Sudoku board to find the unique solution. 

SUDOKU PROCESS 
•  Click on an empty square of the Sudoku board to select it. 
•  Once a square is selected, the left, right, up, and down arrow keys may be used to select a different square. 
•  Click on an element in the list or press a key from 1 to 9 to modify the value in the selected square. 
•  To clear a value in a square, repeat the value that is in the selected square or click the empty square in the element list. 
•  To mark a value as a 'guess', click on the selected square. Click again to unmark it. 
•  Click the 'Edit Pencil Marks' checkbox or right click on a square to toggle the edit mode. (Pencil mark editing allows the player to enter potential values for the square without committing to a value.) 
•  To clear a pencil mark value, repeat the value of the pencil mark in the selected square. 
•  Once the Sudoku puzzle is solved, the player's score is incremented. 

SUDOKU CONSTRAINTS 
•  Every element must occur in each row exactly one time on the Sudoku board. 
•  Every element must occur in each column exactly one time on the Sudoku board. 
•  Every element must occur in each box exactly one time on the Sudoku board. 



SUDOKU GOAL 
•  Correctly fill in the missing elements of the Sudoku board to find the unique solution. 

SUDOKU PROCESS 
•  Click on an empty square of the Sudoku board to select it. 
•  Once a square is selected, the left, right, up, and down arrow keys may be used to select a different square. 
•  Click on an element in the list or press a key from 1 to 9 to modify the value in the selected square. 
•  To clear a value in a square, repeat the value that is in the selected square or click the empty square in the element list. 
•  To mark a value as a 'guess', click on the selected square. Click again to unmark it. 
•  Click the 'Edit Pencil Marks' checkbox or right click on a square to toggle the edit mode. (Pencil mark editing allows the player to enter potential values for the square without committing to a value.) 
•  To clear a pencil mark value, repeat the value of the pencil mark in the selected square. 
•  Once the Sudoku puzzle is solved, the player's score is incremented. 

SUDOKU CONSTRAINTS 
•  Every element must occur in each row exactly one time on the Sudoku board. 
•  Every element must occur in each column exactly one time on the Sudoku board. 
•  Every element must occur in each box exactly one time on the Sudoku board. 



SUDOKU GOAL 
•  Correctly fill in the missing elements of the Sudoku board to find the unique solution. 

SUDOKU PROCESS 
•  Click on an empty square of the Sudoku board to select it. 
•  Once a square is selected, the left, right, up, and down arrow keys may be used to select a different square. 
•  Click on an element in the list or press a key from 1 to 9 to modify the value in the selected square. 
•  To clear a value in a square, repeat the value that is in the selected square or click the empty square in the element list. 
•  To mark a value as a 'guess', click on the selected square. Click again to unmark it. 
•  Click the 'Edit Pencil Marks' checkbox or right click on a square to toggle the edit mode. (Pencil mark editing allows the player to enter potential values for the square without committing to a value.) 
•  To clear a pencil mark value, repeat the value of the pencil mark in the selected square. 
•  Once the Sudoku puzzle is solved, the player's score is incremented. 

SUDOKU CONSTRAINTS 
•  Every element must occur in each row exactly one time on the Sudoku board. 
•  Every element must occur in each column exactly one time on the Sudoku board. 
•  Every element must occur in each box exactly one time on the Sudoku board. 


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