Sudoku solving techniques
Every puzzle on Sudoku Hike is rated by the hardest technique it needs. Learn them in order, from the singles that solve an Easy puzzle to the patterns of Expert. Each guide has a real example from our puzzles and a board to try it on.
Easy
- Hidden singleA digit fits in only one cell of a row, column or box.
- Naked singleA cell has only one possible digit.
Medium
- Locked candidates (pointing)A digit’s places in a box all lie on one line, so it’s removed from the rest of that line.
- Locked candidates (claiming)A digit’s places in a row or column all lie in one box, so it’s removed from the rest of that box.
- Naked pairTwo cells in a unit share the same two candidates, so those digits are removed from the rest of the unit.
- Hidden pairTwo digits fit in only the same two cells of a unit, so the other candidates are removed from those cells.
Hard
- X-WingA digit is confined to the same two columns in two rows (or the same two rows in two columns).
- Naked tripleThree cells in a unit hold only three digits between them.
- Hidden tripleThree digits fit in only the same three cells of a unit.
- XY-WingThree cells with two candidates each force a digit into one of two cells.
- Naked quadFour cells in a unit hold only four digits between them.
- Hidden quadFour digits fit in only the same four cells of a unit.
Expert
- SwordfishThe X-Wing idea with three rows and three columns.
- XYZ-WingAn XY-Wing whose middle cell has three candidates.
- Simple coloringFollows a chain of “one of these two” links for one digit.
- JellyfishThe X-Wing idea with four rows and four columns.