New to Sudoku? The rules are simple—fill every row, column, and 3×3 box with the digits 1–9, no repeats—but knowing where to start can feel overwhelming. These tips will help you approach the grid calmly, avoid common mistakes, and improve quickly.
Start with Easy puzzles
Do not jump straight to Hard or Expert. Easy puzzles have more numbers already placed, so you will often find cells where only one digit is possible. That reinforces the rules and builds the habit of looking at rows, columns, and boxes together. Once Easy feels comfortable, move to Medium. Building up gradually is more rewarding than fighting a grid that is too sparse.
Use notes (candidates) from the beginning
Notes are small digits you put in a cell to mark which numbers might go there. Turn on Notes mode and, for each empty cell, add only the digits that are not already in that row, column, or 3×3 box. At first this takes a bit of time, but it pays off: you will spot “naked singles” (cells with only one candidate) and later techniques like pairs and triples. On Pro Sudoku you can toggle Notes with the Notes button and then tap a number to add or remove a candidate in the selected cell.
Scan for the “last free cell” and “last possible number”
In any row, column, or box, if eight cells are filled, the ninth must hold the one missing digit—that is the “last free cell.” Similarly, for a single empty cell, look at its row, column, and box: if eight different digits are already there, the ninth is the “last possible number” for that cell. Scanning for these two patterns will solve a large part of Easy and many Medium puzzles. Make a pass for rows, then columns, then boxes, and repeat as the grid fills in.
Do not guess—use logic
A well-designed Sudoku has exactly one solution, and every step can be deduced. If you are tempted to try a number “to see if it works,” pause. Either there is a logical move you missed (often a hidden single or a candidate you can remove), or you need to add or update notes. Guessing leads to wrong placements and frustration. Use the Hint button if you are truly stuck; it will reveal the correct number for the selected cell so you can see the logic behind it.
Work in passes and stay organised
Do not randomly jump around the grid. Complete all obvious moves (last free cell, last possible number, naked singles), then update your notes and scan again. Many beginners find it helps to focus on one number (e.g. all 5s) and ask: “Where can 5 go in this row? In this box?” Then move to the next number or the next unit. Staying systematic reduces oversights and makes it easier to spot the next logical step.
Learn one new technique at a time
Once you are comfortable with singles and last-free-cell logic, try one extra technique—for example hidden singles or naked pairs—and look for it in your next few puzzles. Pro Sudoku has a full Techniques section: read one, then practise spotting it in a Medium or Hard puzzle. Adding techniques gradually is more effective than reading the whole list at once.
Use hints and undo without guilt
Hints and undo are there to help. If you are stuck, a hint can reveal the next correct number and often makes the logical pattern clear. Undo lets you take back a wrong move and try again. As you get better, you will need fewer hints, but there is no need to avoid them when you are learning. The goal is to enjoy the puzzle and train your logic, not to suffer in silence.
Ready to put these tips into practice? Play free Sudoku at Pro Sudoku—no sign-up required. Start with Easy, turn on Notes, and work through the grid step by step. For more on why Sudoku is worth your time, see Benefits of Playing Sudoku; for how our puzzles are built, see How We Generate Puzzles.