BEGINNERS · 4 min read

Sudoku for Beginners: Your First Puzzle, Step by Step

If you have never played Sudoku, the grid can look like a wall of numbers. It is much friendlier than it appears. This page explains the rules, walks you through a first puzzle in plain language, and suggests how to get better without frustration.

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The rules in thirty seconds

A Sudoku grid has nine rows, nine columns and nine smaller squares called boxes, each made of three by three cells. Some cells start with numbers, called clues. Your job is to fill every empty cell with a digit from one to nine so that each row, each column and each box contains every digit exactly once.

That is the whole game. There is no arithmetic and no need to add anything up. The digits could just as well be nine different letters or colours. Only the rule about not repeating matters.

Reading the grid

Think of the grid as a set of overlapping groups of nine cells. A cell belongs to one row, one column and one box at the same time. When you place a number, it affects all three groups, because that number cannot appear anywhere else in them.

On PlayDapple, selecting a cell highlights its row, column and box, and highlights other cells holding the same number. Use that help. Looking at the highlighted groups is exactly what experienced players do in their heads.

Your first move: find a crowded box

Look for a box that already has many numbers, say six or seven. The empty cells in that box can only hold the digits that are missing from it. If a box is missing just the digits 2 and 8, each of its two empty cells holds one of them.

Now check each empty cell’s row and column. If a 2 already appears in the same row as one of the empty cells, that cell cannot be 2, so it must be 8, and the other cell is 2. This kind of reasoning, where one cell has only one possible answer, is behind most of your early moves.

Your second move: pick a digit and hunt

Choose a digit that appears several times in the clues, such as 5. For each box that does not yet contain a 5, look at which of its empty cells are not in a row or column that already holds a 5. If only one cell is left, the 5 goes there.

Do this for one digit across the whole grid, then move on to the next digit. Going digit by digit is the most reliable way to find new moves when you feel stuck.

Using notes without drowning in them

When no cell has an obvious answer, turn on Notes and write the possible digits in small type. Start with one box or one row rather than the whole grid. Small notes help you see when two cells share the same pair of candidates, which lets you rule other cells out.

If notes start to feel overwhelming, clear them and go back to scanning. Notes are a tool for hard moments, not a requirement for every cell.

When you make a mistake

Everybody enters a wrong number sooner or later. The signs are a row, column or box in which a digit has nowhere left to go, or two of the same digit in one group, which PlayDapple marks as a conflict. When that happens, undo the last few entries and look for the first one you were not completely sure about.

The Check button shows which entries differ from the solution without changing them. Use it to confirm a suspicion, then try to find the correct number yourself before reaching for a hint.

Choosing a difficulty

Start on Easy. A good sign that you are ready to move up is finishing three Easy puzzles in a row without using hints. Medium puzzles need notes more often. Hard puzzles introduce patterns such as pairs, covered in our full guide to solving techniques. Expert puzzles are for when you enjoy the patterns for their own sake.

There is no shame in staying on a level you enjoy. The puzzles are generated fresh each time, so Easy never runs out.

Healthy habits for relaxed play

Take breaks. If a puzzle has stopped giving moves, step away for a minute or two, or pause the timer. A fresh look often reveals a number you looked at ten times without seeing.

Ignore the clock if it stresses you. Sudoku is a puzzle to enjoy, not a race, and the people who improve fastest are the ones who stay curious about why a number is forced.

Where to go next

Once you are comfortable, read the full Sudoku solving techniques guide for singles, pairs and pointing pairs. If you want a different kind of logic puzzle, try Minesweeper, which also rewards careful deduction, or the Sliding Puzzle, which rewards planning ahead.

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