Variant Sudoku: Not Your Average Number Puzzle

Sudoku Variants as Playful Proof Practice

Variant Sudoku: Not Your Average Number Puzzle

What is the average time you take to solve a 'hard' sudoku? - Quora

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An Introduction To Variant Sudoku: Puzzle 1

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Stuck on this Sudoku variant (#219) Can't get a good start. The numbers in between boxes are what they should add up to. : r/sudoku

Sudoku Assistant -- Solving Techniques