Learn Sudoku Step-by-Step

Introduce Sudoku as a logic-based number puzzle

Explain how the 9×9 grid is made of rows, columns, and boxes

The fundamental rules of Sudoku

Define a 3×3 box and its importance in Sudoku

What makes a puzzle easy or hard

First steps when approaching a new Sudoku

When and how to use hints effectively

Using pencil marks to track possibilities

The simplest solving situation

When a cell can only contain one number

When a digit can only go in one place

When candidates in a box point along a line

When candidates in a line are locked to one box

Two cells with the same two candidates

Two digits that can only go in two cells

Three cells sharing three candidates

Three digits limited to three cells

Four cells sharing four candidates

Four digits limited to four cells

A powerful fish pattern using two rows and two columns to eliminate candidates

Extension of X-Wing to three rows and three columns

The 4x4 fish pattern — the largest practical fish

Three bi-value cells forming a pivot-and-wings pattern for eliminations

Extended XY-Wing where the pivot has three candidates

Chains of bi-value cells for powerful distant eliminations

Using two colors to track conjugate pairs and find contradictions or eliminations

Avoiding deadly patterns that would create multiple solutions

Two conjugate pairs sharing one endpoint to form a turbot fish elimination

A row and column linked through a shared box for single-digit eliminations

Systematic guessing and backtracking as a last resort technique