How to use it
- Choose how many puzzles and per page.
- Download and print.
- Solutions are at the end.
Good to know
- Write candidates in each empty cell, then look for pairs that eliminate options elsewhere.
- Print one per page for room to write notes.
Questions
What makes a sudoku hard?
Fewer givens and, more importantly, the need for techniques beyond simple scanning, such as naked pairs and pointing pairs; the hardest puzzles can need even more advanced patterns.