BlinkuTechniques

Sudoku techniques

How to play, then each technique the hints use, from the easiest. Every article has a real puzzle on which the technique takes the next step.

How to playThe rules and a first move

Beginner · Easy

Full houseA region is missing one digitHidden singleA digit has one place in a region

Medium

Naked singleA cell has only one digit left

Hard

Locked candidatesA digit in a row sits in one boxNaked pairTwo cells hold the same two digitsX-WingA digit in 2 rows, same 2 columnsHidden pairTwo digits fit only two cells

Expert

Naked tripleThree cells hold only three digitsSwordfishA digit in 3 rows, same 3 columnsHidden tripleThree digits fit only three cellsXY-WingThree two-digit cells, one pivotNaked quadFour cells hold only four digitsJellyfishA digit in 4 rows, same 4 columnsHidden quadFour digits fit only four cellsX-ChainFollow one digit, link by link

Master

XY-ChainA chain through two-digit cellsAlternating inference chainA chain mixing both kinds of link