Beginner guide

Sudoku Rules

Sudoku is a logic puzzle, not a math test. Learn the beginner rules, how to use notes and pencil marks, and how to eliminate impossible choices without guessing.

Beginner rules Notes & pencil marks No guessing
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The basic Sudoku rule

Fill every empty cell so each row, each column, and each 3 by 3 box contains the numbers 1 through 9 exactly once. A number can never repeat inside the same row, column, or box.

How to start a Sudoku puzzle

Start with the most crowded areas. If a row, column, or box already has many numbers, it is easier to see which digits are missing. Beginners should look for cells where only one number can fit.

When to use notes

Use notes or pencil marks when two or three numbers could fit a cell. Notes are not guesses; they are reminders of possible candidates. Remove notes whenever another placed number makes them impossible.

Common beginner mistakes

The most common mistake is placing a number because it looks likely instead of proving it fits. Another mistake is writing too many notes, which can make the board harder to read.

How to use notes in Sudoku

For beginners, notes work best when they stay small and useful. Write only the realistic candidates for a cell, then scan the row, column, and box again whenever a new number is placed.

Beginner Sudoku tips

Look for singles first, check the most crowded 3 by 3 boxes, and avoid guessing. If you get stuck, use a hint or solver to understand the next logical step instead of filling a random number.

Beginner method

A simple way to solve your first Sudoku puzzle

Beginners do not need advanced techniques to get started. The most reliable first method is scanning: compare one row, one column, and one 3 by 3 box at a time, then place a number only when every other option is impossible.

  1. Start with crowded boxes. A 3 by 3 box with five or six numbers already filled usually has fewer possibilities to test.
  2. List the missing digits. If a box is missing 2, 4, and 9, check each empty cell against its row and column.
  3. Place only proven singles. If only one missing digit can fit a cell, place it. If more than one can fit, use notes instead.
  4. Repeat after every placement. One new number can unlock a row, column, or box that was unclear a minute ago.

Mini example

If a row is missing 3, 6, and 8, and one empty cell already sees 3 in its column and 8 in its box, that cell must be 6. That is the basic logic behind many beginner moves.

Beginner searches

Sudoku questions beginners usually ask

Rules pages should answer the first real problems a new player has: what the goal is, how notes work, and what to do when the obvious numbers run out.

Rules

How to play Sudoku for beginners

Start with rows, columns, and 3 by 3 boxes, then place only numbers you can prove.

Notes

Sudoku notes for beginners

Use small candidate numbers to remember possibilities without turning the grid into clutter.

Pencil marks

Sudoku pencil marks for beginners

On paper, pencil marks serve the same role as online notes: they track candidates until logic removes them.

What notes should look like

Good notes are short. Write only candidates that survive the row, column, and box checks. If every cell contains every number, the notes stop helping.

Why guessing causes trouble

A wrong guess can look fine for several moves before creating a contradiction. Logic keeps the puzzle traceable and makes mistakes easier to fix.

When to move up from easy

Try Medium puzzles when you can finish Easy puzzles without guessing and when notes feel helpful instead of confusing.

Beginner FAQ

Do I need math to play Sudoku?

No. Sudoku uses numbers, but solving is based on logic and placement, not arithmetic.

What is the easiest Sudoku strategy?

Look for a cell where only one number can fit after checking its row, column, and box. This is often called a single.

Should beginners use a timer?

A timer is useful for tracking progress, but beginners should focus on accuracy before speed.

What are pencil marks in Sudoku?

Pencil marks are small candidate numbers written in an empty cell. They help you remember which digits might still fit there.

Should I guess in Sudoku?

Beginners should avoid guessing when possible. A well-made Sudoku can be solved by logic, and hints can help you find the next proven move.