Basic Sudoku techniques

Basic Sudoku techniques: the foundation moves

The moves that carry easy and medium boards before advanced patterns become necessary.

This page covers the foundation: full house completions, naked and hidden singles, clean note-taking, naked pairs, and locked candidate patterns like pointing and claiming.

What you will practice

Move from the simplest board read to the first true elimination patterns. Each slide uses one hardcoded board so the technique stays concrete.

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  • Spot full house completions and naked singles instantly.
  • See the difference between naked singles and hidden singles on real boards.
  • Use notes as working memory when the answer is not ready yet.
  • Graduate into naked pairs and locked candidates before advanced patterns.

Basic walkthroughs

Move from the simplest board read to the first true elimination patterns. Each slide uses one hardcoded board so the technique stays concrete.

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Column 4 has only one empty cell; the missing digit 7 must go there. The bottom-center box has only one empty cell; the missing digit 6 must go there.

Easiest completion

Full House

A full house is the simplest Sudoku move. One row, column, or box has exactly one empty cell, so the missing digit is obvious.

How to read it

  1. 1Scan every row, column, and box for units with exactly one empty cell.
  2. 2Identify which digit 1–9 is missing from that unit.
  3. 3Place it immediately and rescan the connected units.

Why it matters

Full houses are free wins. Spot them fast and they often set off a chain of further placements.

Always scan for full houses first. Look for any row, column, or box with eight digits filled—the ninth cell must get the missing digit.

Technique 1 of 8

Basic technique questions

Which technique should I learn first?

Start with full houses, naked singles, and hidden singles. If those still feel slow, pairs and locked candidates will only feel heavier than they need to.

When should I begin using notes?

Use notes when a cell still has multiple realistic candidates and the easy placements have dried up. They are most useful once the board stops handing you obvious singles.