How to Play Sudoku: A Beginner's Guide to Solving Your First Puzzle
August 9, 2026
Sudoku looks like a math game, but there is no arithmetic in it at all. It is a pure logic puzzle: every number you place is either certainly right or certainly wrong, and a well-made puzzle never forces you to guess. This guide walks a complete beginner from the rules to a reliable way of solving your first easy puzzles.
The rules in thirty seconds
You get a 9×9 grid, divided into nine 3×3 boxes, with some numbers already filled in. Your job is to fill every empty cell with a digit from 1 to 9 so that each row, each column, and each 3×3 box contains every digit exactly once. No repeats in a row, a column, or a box — that is the entire rulebook. The starting numbers are called givens, and a proper puzzle has exactly one solution.
How to actually start
Beginners often stare at the whole grid and freeze. Instead, pick one number that appears often among the givens — say there are six 5s on the board — and scan for where the remaining 5s must go. Because each 5 claims its row, column and box, the existing ones rule out most empty cells. When only one cell in a box can hold a 5, write it in. This habit is called scanning, and it alone solves most easy puzzles.
Beginner mistakes that get you stuck
- Guessing. If you are not certain, do not write it. One wrong digit quietly poisons everything built on top of it, and you will not find out until the grid contradicts itself much later.
- Staring instead of scanning. Progress comes from checking one number or one unit at a time, not from waiting for the whole grid to speak to you.
- Ignoring the almost-full units. A row, column or box with seven or eight digits filled is nearly free progress — the missing digits can usually be placed instantly.
- Writing pencil marks everywhere from the start. On easy puzzles, marking every candidate in every cell buries the logic under clutter. Scan first; save notes for when you are genuinely stuck.
- Losing patience after one pass. Every number you place unlocks new deductions elsewhere. Loop back over the grid — the second and third passes are always easier than the first.
When scanning is not enough
On harder puzzles you will eventually hit a wall where no cell can be placed by scanning alone. That is where pencil marks come in: write the possible candidates in the corner of the stuck cells, and look for a cell with only one candidate left, or a number that fits only one cell in its unit. These two ideas — naked singles and hidden singles — carry you through most medium puzzles, and our Sudoku techniques guide takes it from there all the way to the X-Wing.
A good habit for every level
After you place a digit, glance at the three units it touches — its row, its column and its box — to see what became newly forced. Strong solvers do not scan randomly; they follow the consequences of each move. This one habit turns solving from a hunt into a chain reaction, and it is exactly how the fast times on our leaderboard are set.
Learn the rules, scan one number at a time, never guess, and your first finished grid stops being a matter of luck and becomes a matter of minutes. Our Sudoku has three difficulties and a ranked leaderboard when you are ready to race.