Do I ever need to guess in sudoku?

No. A well-made sudoku can always be solved by logic. If you feel you must guess, look again for singles or pairs.

How many hints do I get?

Three per puzzle. Each one fills in the correct digit in a cell.

Do notes update by themselves?

Yes. When you place a correct digit, it is removed from the notes of its row, column and box.

Sudoku Tips for Beginners: How to Solve Any Grid

Every sudoku has one solution that can be found by logic alone, without guessing. The trick is knowing which patterns to look for. This guide starts with the basic techniques that solve most Easy and Medium grids, then adds the tools you need for Hard puzzles, plus how to use our notes and hints well.

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Start by scanning

Pick a digit, say 5, and look at each 3x3 box that does not have one yet. Rows and columns that already contain a 5 rule out cells in that box. If only one cell is left, the 5 goes there. Work through all nine digits this way. On Easy grids, scanning alone can solve most of the puzzle.

Find the singles

A naked single is a cell where only one digit fits once you check its row, column and box. A hidden single is a digit that can go in only one cell of a row, column or box, even if that cell has other candidates. Look first at rows, columns and boxes that are nearly full, where singles are easiest to spot.

Use notes properly

Turn on Notes (N on a keyboard) and pencil every possible digit into the tricky cells. When you place a correct digit, our game removes it from the notes in the same row, column and box automatically. Cells with just two candidates become stepping stones that unlock the rest of the grid.

Tricks for harder grids

If two cells in a row, column or box share the same two candidates and nothing else, those two digits must go in those cells. Remove them from every other cell in that unit. And if a digit's candidates inside a box all sit in one row, that digit cannot appear elsewhere in that row. These two ideas crack most Hard puzzles.

Avoid the three-mistake limit

Every wrong digit adds to the mistake counter, and three ends the puzzle. Only enter a digit when you can prove it is the only option. If you are unsure, use notes instead. You also have three hints per puzzle, which fill in a correct cell. Save them for the moment you are truly stuck, not the first time it gets hard.

Questions

Do I ever need to guess in sudoku?: No. A well-made sudoku can always be solved by logic. If you feel you must guess, look again for singles or pairs.
How many hints do I get?: Three per puzzle. Each one fills in the correct digit in a cell.
Do notes update by themselves?: Yes. When you place a correct digit, it is removed from the notes of its row, column and box.

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