Internet Sudoku

Techniques

Sudoku techniques

Sudoku techniques are named ways to prove a number belongs in a square. Start with the simple patterns below before moving to harder candidate eliminations.

Start with singles

Singles are the foundation of clean Sudoku solving. They do not require guessing; they come from checking which digits remain possible in a cell, row, column, or box.

The Internet Sudoku Explain Next Move feature starts here because singles are easy to verify and useful for beginners.

How to use this guide

Read the technique, then play a daily puzzle and look for the same pattern on the board. If you get stuck, use Explain Next Move to see whether a simple single is available.

Technique guides

Naked singleA square has only one possible digit left.Hidden singleA digit has only one possible position in a row, column, or box.Play Daily SudokuPractice the techniques on today's puzzle.Sudoku tipsReview broader habits for notes and scanning.

Sudoku Tips

Sudoku gets easier when you solve with a repeatable scan instead of searching the whole grid at once.

Tip 1: Look for rows, columns, or 3 by 3 boxes that already contain several numbers. The more filled-in an area is, the fewer places a missing digit can go.
Tip 2: Work one number at a time. Scan every box for where that number can still fit, then compare those open spots with the crossing rows and columns.
Tip 3: Use notes when a square has only a few real candidates. After every confirmed number, clean up notes in the same row, column, and box.