--- title: "How to Start a Sudoku: First Moves, Step by Step | Sudoku Flow" description: "Where to begin on a new Sudoku: the squares to look at first, a real Easy puzzle solved move by move by our hint engine, and when to start using notes." url: https://sudokuflow.com/guides/how-to-start-sudoku/ language: en last_modified: 2026-11-05 --- [Sudoku guides](https://sudokuflow.com/guides/) # How to Start a Sudoku: The First Five Minutes Where to begin on a new Sudoku: the squares to look at first, a real Easy puzzle solved move by move by our hint engine, and when to start using notes. Updated 2026-11-05 ## Quick answer Start where the grid is fullest. A row, column or 3×3 box with one empty square left is a free move: the missing digit goes there. Then take one digit that already appears often and check each box for the one square it can go in. Leave notes for later: on an Easy puzzle you rarely need them. - Every row, column and 3×3 box holds 1 to 9 once. - Start with the fullest row, column or box. - Then scan one digit at a time across the boxes. - Place a digit only when you can say why it goes there. - Start notes when scanning stops giving you moves. ## The rule in one line Fill the grid so that every row, every column and every 3×3 box holds the digits 1 to 9 exactly once. Everything below follows from this one rule. You never need to add numbers up, and every puzzle in our bank can be solved by logic alone, without guessing. ## Look for the fullest row, column or box A row, column or box with only one empty square is a free move: one digit is missing, and it can only go there. Our hint engine calls this the last remaining cell, and on Easy puzzles it is usually the first thing it finds. When a row, column or box has two or three empty squares, check each of them against its own row, column and box: often only one of the missing digits fits. ## Then scan one digit at a time Pick a digit that already appears several times, say 5. For each box that still has no 5, look along the rows and columns that pass through it: every 5 in those lines rules out a square. When only one square is left in the box, the 5 goes there. This is called a hidden single, and in our bank of 60,000 puzzles it is the step that decides every Medium puzzle. ## A real Easy puzzle, move by move This is the first Easy puzzle on our site. These are the first 6 moves our hint engine finds on it, in the order it finds them, each with the reason it gives. The engine always takes the easiest move on the board, so this is also a good order for a person. ```text 3 6 . | . 1 7 | 8 . . . . 8 | . . 3 | . 4 . 1 2 5 | 8 6 4 | 3 9 7 ------+-------+------ . 3 7 | 4 9 5 | 1 . 2 . 9 . | 3 8 1 | 7 5 . 8 5 1 | 6 7 2 | 4 3 9 ------+-------+------ 7 . 3 | 1 . 9 | . . 8 . 1 6 | . . 8 | . 7 . 5 8 9 | 7 4 6 | 2 1 3 ``` *The first Easy puzzle on Sudoku Flow, with the engine's first 6 moves filled in.* 1. **Row 9, column 2: 8** ([Last Remaining Cell](https://sudokuflow.com/lessons/lastRemaining/)). There is only one empty cell left in this row. The only possible number is 8! 2. **Row 8, column 6: 8** ([Last Remaining Cell](https://sudokuflow.com/lessons/lastRemaining/)). There is only one empty cell left in this column. The only possible number is 8! 3. **Row 6, column 4: 6** ([Last Remaining Cell](https://sudokuflow.com/lessons/lastRemaining/)). There is only one empty cell left in this box. The only possible number is 6! 4. **Row 6, column 2: 5** ([Last Remaining Cell](https://sudokuflow.com/lessons/lastRemaining/)). There is only one empty cell left in this row. The only possible number is 5! 5. **Row 3, column 3: 5** ([Nearly Complete](https://sudokuflow.com/lessons/nearlyLastRemaining/)). This row only needs 5, 8. 8 is already in the same column, so it cannot go in this cell. Only 5 remains for this cell! 6. **Row 3, column 4: 8** ([Last Remaining Cell](https://sudokuflow.com/lessons/lastRemaining/)). There is only one empty cell left in this row. The only possible number is 8! [Play this puzzle →](https://sudokuflow.com/play/easy/#1) ## When to start using notes Notes, the small digits you write in a square to remember what can still go there, are not needed for the first moves. Start them when scanning stops giving you placements, which on Easy and Medium puzzles rarely happens. From Hard on, every puzzle in our bank needs at least one step that works on notes, such as a pointing pair. ## Three habits that save puzzles - Place a digit only when you can explain why it goes there. A guess that happens to fit can break the puzzle twenty moves later. - After each placement, look at the same row, column and box again: a new digit often opens the next move right there. - If you get stuck, check for a mistake before looking for a harder technique: a digit twice in a row, column or box, or a square with no possible digit. ## Practice Every Find the Mistake puzzle on this site has exactly one wrong digit, and you can play each board right on its page. [Play the puzzles →](https://sudokuflow.com/puzzles/) ## Sudoku guides - [How to Find a Mistake in Sudoku](https://sudokuflow.com/guides/find-a-mistake/) - [7 Common Sudoku Mistakes and How to Avoid Them](https://sudokuflow.com/guides/common-mistakes/) - [Why Won't My Sudoku Solve? A Checklist](https://sudokuflow.com/guides/sudoku-wont-solve/) - [Naked Single vs Hidden Single](https://sudokuflow.com/guides/naked-single-vs-hidden-single/) - [Pointing Pair vs Box/Line Reduction](https://sudokuflow.com/guides/pointing-pair-vs-box-line-reduction/) - [X-Wing vs Swordfish](https://sudokuflow.com/guides/x-wing-vs-swordfish/) - [Stuck on a Hard or Expert Sudoku? The Technique You Need Next](https://sudokuflow.com/guides/stuck-on-hard-sudoku/) - [Sudoku Tips That Actually Work (and Is There a Formula?)](https://sudokuflow.com/guides/sudoku-tips/) - [How to Teach a Child Sudoku: 4×4, Then 6×6, Then 9×9](https://sudokuflow.com/guides/teach-kids-sudoku/) - [Can Every Sudoku Be Solved Without Guessing?](https://sudokuflow.com/guides/solve-without-guessing/) - [What each Sudoku difficulty level asks of you](https://sudokuflow.com/data/sudoku-difficulty-levels/) - [Sudoku facts](https://sudokuflow.com/guides/sudoku-facts/) - [Sudoku checker](https://sudokuflow.com/tools/sudoku-checker/) - [Sudoku for kids](https://sudokuflow.com/printables/kids/) - [Find the Mistake Sudoku](https://sudokuflow.com/find-the-mistake/) ![Sudoku app icon](https://sudokuflow.com/assets/app-icon.png) ## Want more boards like this? We also make a Sudoku app for iPhone, iPad, Mac and Android. There are no ads in it at all, it works offline, and when you ask for a hint it shows you the technique instead of just filling in a number. [App Store iPhone, iPad, Mac](https://apps.apple.com/app/apple-store/id6502922368?pt=125379530&ct=sudokuflow_web&mt=8) [Google Play Android](https://play.google.com/store/apps/details?id=com.rubigogames.sudoku&referrer=utm_source%3Dsudokuflow%26utm_medium%3Dweb%26utm_campaign%3Dsite) Sudoku Flow is made by Rubigo Games, the developer of the Sudoku app recommended on this site.