Sudoku for Beginners: How to Solve Your First Puzzle, Step by Step

If you've never finished a Sudoku puzzle, this guide will get you there. There's no maths involved, no guessing required, and no special talent needed — just three simple rules and a way of looking at the grid that anyone can learn in a few minutes. We'll cover the rules, walk through the first techniques with real grid diagrams, solve a puzzle together, and finish with the questions beginners ask most.

What is Sudoku?

A Sudoku is a 9×9 grid, divided into nine smaller 3×3 boxes. Some cells start with numbers already filled in — these are the "givens" — and your job is to fill in all the rest. Despite the numbers, it isn't a maths puzzle at all: you never add, subtract, or calculate anything. The digits are just nine different symbols. You could play with nine colours or nine letters and it would be exactly the same game. It's pure logic.

Every proper Sudoku has exactly one solution, and you can always reach it by reasoning alone. That's the most important thing to internalise as a beginner: you never have to guess. If you ever feel stuck enough to guess, it simply means there's a logical step you haven't spotted yet — not that the puzzle is unfair.

The three rules

There are only three, and you already half-know them:

1. Each row (going across) must contain the digits 1 to 9, with no repeats.
2. Each column (going down) must contain 1 to 9, with no repeats.
3. Each 3×3 box must contain 1 to 9, with no repeats.

That's the entire game. A "house" is the general word for any one of these — a row, a column, or a box — and much of solving comes down to asking questions about a single house at a time. Our full rules explainer covers all of this with interactive examples if you'd like to see it in motion first.

Your first move: scanning

The single most useful habit in Sudoku is scanning — picking one digit and asking, "where can this number go?"

Here's how it works. Pick a digit that already appears several times on the board — say the 5s. Now look at a 3×3 box that's still missing its 5. Any row or column crossing that box that already contains a 5 "blocks" every cell it passes through: a 5 can't go there, because that row or column already has one. Cross off enough cells and often just a single legal spot is left. That's where the 5 goes.

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1Um 5 nesta coluna e um 5 nesta linha já bloqueiam quatro células da região.

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2Mais dois 5s — numa linha e numa coluna — bloqueiam o restante, exceto uma célula.

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3Só esta célula continua aberta. O 5 vai aqui.

Notice the rhythm in those steps: existing digits project invisible lines across the grid, and those lines corner a number into one cell. Work digit by digit, starting with the numbers that already appear most often — they give you the most lines to work with. This one technique will finish a surprising number of easy puzzles on its own. There's a dedicated scanning walkthrough if you'd like to see more examples.

When a single cell gives itself away: naked singles

Scanning asks "where can this digit go?" The flip side is to look at one empty cell and ask, "what can go here?"

If that cell's row, column, and box between them already contain eight different digits, then only one digit is left unaccounted for — and it must go in that cell. This is called a naked single, and it's the cleanest placement in the game. No single house does all the work; it's the three of them combined that leave just one option.

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1A linha 5 já tem 2, 6, 8 e 9 colocados — quatro dígitos descartados.

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2A coluna 5 também descarta o 1 e o 5 — seis dígitos eliminados.

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3A região central descarta o 7 e o 3 — oito dígitos eliminados.

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4Só resta o 4. Ele precisa ir aqui.

Watch how the row rules out some digits, the column rules out more, and the box finishes the job — until only one candidate survives. Once you start keeping track of what each cell can't be, naked singles jump out at you. The naked single guide breaks this down further.

The most powerful beginner technique: hidden singles

Here's the technique that will place more numbers for you than any other, so it's worth training your eye for. A hidden single is a digit that has only one legal home in a house — even though that cell might still look busy, with room for several other digits.

The trick is that you find it by scanning for a digit within a single house, not by looking at a cell's candidates. Ask: "in this box, where can the 7 actually go?" If seven of the nine cells are blocked by a 7 elsewhere in their row or column, and one more already has a number, then the 7 has exactly one home — even if that cell could, on the surface, also hold a 3 or a 4.

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1Duas linhas já têm um 7, bloqueando quatro células desta região.

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2Duas colunas também têm um 7, bloqueando mais três.

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3Só esta célula continua aberta — o 7 vai aqui.

Hidden singles are called "hidden" precisely because they don't look obvious — the winning cell isn't empty-looking or down to one option, it just happens to be the only place the digit fits. Get in the habit of asking, for each digit in each house, "is there only one spot left for it?" and you'll unlock puzzles that felt stuck. The hidden single guide has more.

Putting it together: a full walkthrough

Here's the rhythm for solving an easy puzzle from start to finish. Almost every easy grid falls to just these steps, looped:

1. Scan every digit, 1 through 9. For each one, look at the boxes it's missing from and see whether the lines from its existing placements corner it into a single cell.
2. Every time you place a digit, rescan. A new number often unlocks two or three more placements in a chain — this is where the puzzle starts to "open up" and feel satisfying.
3. When scanning stalls, switch to cells. Look for naked singles: cells where the row, column, and box between them have left only one option.
4. Hunt hidden singles. For each digit, check whether any house has just one spot it can still go. This is the step beginners skip most, and it's the most productive one.
5. Repeat until the grid is full. On an easy puzzle, scanning plus singles will always be enough — no advanced techniques, no guessing.

What to do when you get stuck

Getting stuck almost never means the puzzle is broken. It means you've run out of the particular thing you were looking for — not out of logic. When it happens, work back through the checklist deliberately:

• Rescan each digit slowly. It's easy to miss a placement when scanning quickly. Go 1 through 9 and give each digit its full sweep.
• Re-hunt hidden singles. The last few numbers you placed may have created new ones.
• Check your most-filled houses. A row, column, or box with only one or two gaps is often one deduction away from resolving.

If you'd like a complete map of what to try and in what order — all the way up to advanced techniques for when you graduate to harder puzzles — our strategy guide lays out the full hierarchy, and the techniques index has an animated walkthrough for every method.

Common beginner mistakes

A few habits trip up almost every new player. Avoiding them will speed up your progress more than any single technique:

• Guessing when stuck. The cardinal sin. A wrong guess can corrupt the grid invisibly and cost you a dozen moves before the contradiction shows up. If you can't justify a placement, don't make it.
• Filling a single but forgetting to follow up. Every placement changes what's possible elsewhere. Rescan immediately.
• Only looking at boxes. Rows and columns block cells too. Scan all three kinds of house.
• Ignoring pencil marks on harder puzzles. On easy grids you can hold candidates in your head, but the moment you move up a level, start using notes — they're the working surface every later technique depends on.

Frequently asked questions

Do I need to be good at maths to play Sudoku?

Not at all. Sudoku uses digits, but there's no arithmetic — no adding or calculating. It's a pure logic puzzle. The numbers are just nine distinct symbols.

Is it ever okay to guess?

No. Every proper Sudoku has a single solution reachable by logic alone. A guess that turns out wrong can send you many moves down a broken path before you notice. When you're stuck, there's always a technique you haven't applied — not a need to guess.

How long should an easy puzzle take?

Once you're comfortable with scanning and singles, three to six minutes is typical. Speed comes naturally as pattern recognition improves — don't rush it early on.

What should I do after I can finish easy puzzles?

Move up one difficulty and start keeping pencil marks. That's when techniques like naked and hidden pairs come into play. The 5 techniques every beginner should learn first is the natural next read.

Why does my puzzle have more than one solution?

A proper puzzle never does — exactly one solution is guaranteed. If a grid seems to have two, either a given was mis-entered or it isn't a valid puzzle. Every puzzle on this site is verified to have a unique solution.

Ready to try one?

The best way to learn is to solve. Start an easy solo puzzle and work through the rhythm above — scan, place, rescan, hunt singles. When you can finish one without hints, you're no longer a beginner. After that, the daily challenge gives you one fresh puzzle a day to build a habit around.