Easy, medium or hard, by the steps it needs.
How the Puzzle maker makes sudoku with exactly one answer and rates each by the hardest step a person needs, with answer pages. Free, nothing sent.
By Suraj Kumar3 min read
The number of clues says little about how hard a sudoku is. What matters is the hardest step you have to take.
One answer, checked.
Each puzzle starts as a full grid filled in a random order. Clues are taken away in pairs that mirror through the middle, and after each pair a solver counts the answers; a pair is put back if the puzzle would have two. So every puzzle has exactly one answer. No puzzle with fewer than 17 clues can have only one, as McGuire and others proved by search in 2012.
Rated by the hardest step.
A second solver works as a person does. Easy puzzles need only singles: a square with one number left, or a number with one place left. Medium ones also need pairs and pointing: two squares sharing two numbers, or a number held to one line of a box. Hard ones need triples, an X-Wing, or trying a number to see where it leads.
Each puzzle is printed with the level it really came out at; when many tries do not reach the level asked, the page says so.
One to six a page.
Print up to 24 puzzles, one, two, four or six to a page, with their answers after them, the given numbers in bold and the answers in grey.
Further reading
Topics: printable sudoku · sudoku difficulty · easy sudoku · hard sudoku printable · sudoku with answers
A little less theory. A little more doing.
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