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Understand the deduction before filling the square.
Work through candidate patterns and original examples explaining why an elimination is valid. Each lesson makes the relevant rows, columns and boxes visible.
2 published guides
Printable Puzzle Kit grades Sudoku by a complete human-technique solve: naked singles, hidden singles, locked candidates and naked pairs—not clue count.
Read the guide : How our Sudoku difficulty levels workLearn the three rules of 9×9 Sudoku, find a first candidate and understand why unique solutions and difficulty are different checks.
Read the guide : Sudoku rules and a practical first moveA little more context
No. Pencil marks record candidates consistent with known digits. A deduction removes candidates or fixes a value for a stated reason.
Clue count alone does not determine difficulty. The deductions needed, their visibility and the solving method affect the experience.
Rob