Hard Sudoku: uses, sizes and printing tips
Challenging sudoku with only about 27 given numbers — you will need pencil marks and techniques like pairs and pointing. Four puzzles per page, each with a single solution and an answer key.
How to print it
- Choose the paper size (US Letter, A4, Legal, A5 or Half Letter) and portrait or landscape — the page updates as you change settings.
- Choose the game and how many boards, cards or puzzles fit on a page; for bingo and sudoku click New numbers for a fresh set.
- Add a title or a name/date header if you want, or keep the page plain.
- Click Print / Save as PDF. In the print dialog choose “Actual size” (100%) and turn off “Headers and footers”.
Tips
- Take a break and come back — a fresh look often reveals the next step.
- Every set of numbers has its own link — share the address and others get exactly the same cards or puzzles.
- Laminate a sheet or slide it into a sheet protector and use dry-erase markers to play again and again.
FAQ
What techniques help with hard sudoku?
Write candidate numbers in small print, then look for naked pairs, hidden singles and pointing pairs to eliminate candidates.
Is there a unique solution?
Yes — every puzzle is checked to have exactly one solution.
Are the puzzles and cards really random?
Yes. Bingo cards and sudoku puzzles are generated in your browser; every sudoku has exactly one solution. Click New numbers as often as you like.
Is it free, and do I need an account?
It is completely free with no sign-up and no download. Change the settings, print it or save it as a PDF, and bookmark the address — your settings are stored in the link.
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↑ Customize and print the Hard Sudoku