Free Sudoku Puzzles Online - Number Place - Hard

Frequently Asked Questions

What techniques do I need to solve a Hard puzzle?

Hard requires Naked Pairs and Pointing Pairs — techniques that read the interactions between candidates. Managing candidates with the notes feature becomes a prerequisite at this level.

What should I master before trying Hard?

You should be able to solve Medium puzzles consistently using Hidden Singles. Jumping ahead too early leaves you short of several techniques at once, which makes it hard to tell what you are missing.

What should I do when I am completely stuck on a Hard puzzle?

If you have tried all the basic techniques and still cannot find a cell to fill, that position may require a more advanced technique. If it is an oversight, re-checking the three constraints in order often reveals the way forward.