DailyRanks

Sudoku Strategies

Nine techniques, from Easy to Master. Each with a real puzzle.

Learn them in this order

Naked SingleA cell where only one number is leftEasyHidden SingleA number that fits in only one cell of a unitEasyNaked PairTwo cells, same two candidates: clear those numbers from the rest of the unitHard–ExpertHidden PairTwo numbers, same two cells: clear the cells' other candidatesHard–ExpertNaked TripleThree cells, three numbers: clear those numbers from the rest of the unitHard–ExpertPointing PairA box's candidates in one line clear the rest of the lineHard–ExpertX-WingOne number, two rows, same two columns: clear it from those columnsMasterSwordfishOne number, three rows, same three columns: clear it from those columnsMasterXY-WingPivot and two pincers clear their shared numberMaster

How the levels work

Sudoku techniques build on each other. The basics (singles) solve every Easy and Medium puzzle. Hard puzzles may need pairs and pointing; Expert puzzles always do. Master puzzles add X-Wing, Swordfish or XY-Wing.

On puzuru, every puzzle is graded by a program before you see it: it must have exactly one solution and be solvable with the techniques of its level. So once you know the techniques below, you know what each level will ask of you.

Words used on these pages

Candidate: a number that could still go in an empty cell. Notes (pencil marks) are how you write candidates down.

Unit: a row, a column or a 3x3 box. Each unit holds 1 to 9 exactly once.

Sees: two cells see each other if they share a row, column or box, so they can't hold the same number.

General tips

Always go back to singles after any removal. Advanced techniques rarely place a number directly; they clear candidates so that a single appears.

Fill in all candidates before hunting for pairs, pointing or wings. Patterns are nearly invisible without notes.

Work one number at a time for pointing, X-Wing and Swordfish, and look at two-candidate cells for pairs and XY-Wing.

Beyond Master: Extreme

Extreme puzzles stall even with everything on this page. You need deeper reasoning, such as following chains of candidates (if this cell is 4, then that one is 7, then...).

Each Extreme puzzle still has exactly one solution. Try one when the techniques above feel easy.

Try an Extreme puzzle →　Rules and basics →

FAQ

What is the best Sudoku strategy for beginners?

Learn hidden singles and naked singles first. They solve every Easy and Medium puzzle on puzuru.

Which technique should I learn after the basics?

Naked pairs and pointing pairs. Expert puzzles on puzuru always need them, or their cousins: hidden pairs and triples.

Do I ever need to guess?

Not on puzuru's Easy to Master levels. Every puzzle there is checked to be solvable without guessing, using singles, pairs and triples, pointing, X-Wing, Swordfish and XY-Wing. Extreme puzzles need deeper reasoning such as chains.

More games

SolitaireClassic Klondike. Every deal is checked to be winnable.Mahjong SolitaireClear the board by matching pairs of tiles.Spider SolitaireBuild runs from King to Ace. Every deal is verified winnable.CheckersThe classic jump-and-capture board game. Five computer levels, or play a friend on the same device.FreeCellFour free cells, pure strategy. Classic game numbers, every deal verified winnable.HeartsThe classic trick-taking card game. Play against 3 computer opponents.Reversi (Othello)The classic disc-flipping board game. Five computer levels, or play a friend on the same device.GomokuGet five in a row before your opponent. A 15×15 board, five computer levels, or play a friend on the same device.MancalaSow stones and fill your store. The popular six-pit, four-stone rules, five computer levels, or play a friend on the same device.Four in a RowDrop discs and line up four before your opponent. A 7×6 board, five computer levels, or play a friend on the same device.Five DiceRoll five dice up to three times, make combinations and fill 15 boxes. Go for a high score solo, or play the computer or a friend.Tic-Tac-ToeGet three in a row before your opponent on a 3×3 grid. Five computer levels, or play a friend on the same device.Mahjong ConnectJoin matching mahjong tiles with a line of up to two turns. Three board sizes up to the classic 8×17. Every deal can be cleared.DaifugoThe Japanese climbing card game: be first to empty your hand. 8-stop, revolution and the card exchange, 5 rounds against 3 computer players.Gin RummyDraw, discard and meld your hand into sets and runs. Knock with 10 or less deadwood or go gin. One-on-one against the computer, first to 100 wins.Word SearchFind the hidden words across, down and diagonally. Ten themes, three sizes from 8×8 to 15×15, a new puzzle every time, and printable.SevensBuild each suit out from the 7s and be first to empty your hand. Up to 3 passes per round, 5 rounds against 3 computer players.Tower of HanoiMove the whole stack of disks to the right rod, one disk at a time, never placing a larger disk on a smaller one. 3 to 8 disks, aim for the minimum moves.Sliding PuzzleSlide the tiles into the empty space to put the numbers in order. 3×3, 4×4 (the classic 15 puzzle) and 5×5. A new, solvable puzzle every time.Yukon SolitaireA Klondike-style solitaire with no stock pile. Any face-up card moves together with the cards on top of it. Every deal can be won.Scorpion SolitaireBuild down in suit and complete four columns from King to Ace. Any face-up card moves together with the cards on top of it.SpadesThe classic partnership card game where spades are trump. Team up with a computer partner.BackgammonRoll the dice and race your 15 checkers home. Five computer levels, or play a friend on the same device.2048Slide and merge matching tiles to reach 2048. Boards from 3×3 to 6×6, with undo.MazeDrag from start to exit. 8×13 to 30×53, a new maze every time, and printable.NonogramFill the grid from row and column number clues. 5×5 to 20×20, every puzzle solvable by logic alone.Matching GameTurn over two cards and match the pictures. Animals, food and vehicles, 8 to 24 pairs.ConcentrationThe classic memory card game: turn over two cards and match pairs. Four levels, 8 to 24 pairs.TriPeaks SolitaireChain cards one higher or lower to clear three peaks of cards.Golf SolitairePlay cards one higher or lower to clear all seven columns. Every deal is winnable.Pyramid SolitairePair cards that add up to 13 to clear the pyramid. Every deal is winnable.MinesweeperOpen every safe cell using the numbers. Every board can be solved by logic alone.Killer SudokuNo given numbers. Solve it from the cage sums alone.