What "difficulty" actually means
Not the number of given digits — that is a poor guide, and puzzles with the same count vary enormously. Difficulty is which solving techniques a puzzle requires. An easy grid falls to scanning alone. A hard one needs candidate elimination and patterns like naked pairs or X-wings.
Every puzzle here has exactly one solution, which is what separates a real sudoku from a grid of numbers. A puzzle with two solutions can only be finished by guessing, and that is a defect rather than a challenge.
Printing a set
Several puzzles per sheet suits a class or a journey; one per page is easier for anyone who writes candidate numbers in the cells, which is most people past the easy level.
The solutions print separately so a sheet can be handed out without them.
Frequently asked questions
Does every puzzle have exactly one solution?
Yes. A grid with more than one can only be completed by guessing, which is a defect rather than difficulty.
Why do two puzzles with the same number of givens feel different?
Because difficulty is about which techniques are needed, not how many digits are shown. The count is a weak guide.
Can I print the answers separately?
Yes — solutions are on their own sheet, so puzzles can be handed out without them.
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