11
Lesson 11: Naked Triples
⏱ 20 minThree cells in a unit that collectively contain only three candidates — eliminate those candidates everywhere else in the unit.
Triple detectionCollective candidatesUnit elimination
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Advanced Level
Master the techniques that separate good solvers from great ones. Pattern recognition at a new level.
Built on the foundation of the Intermediate level, this section of the Sudoku Academy teaches the powerful fish and pair strategies needed to conquer Hard Sudoku puzzles — and begin your path toward Expert Sudoku solving.
Lessons 11–15⏱ ~120 min total🆓 Free
Lesson List
12
Lesson 12: Hidden Pairs
⏱ 20 minTwo digits that appear as candidates in only two cells of a unit — remove all other candidates from those cells.
Pair frequencyCandidate removalHidden vs Naked
13
Lesson 13: X-Wing
⏱ 25 minA digit appearing in exactly two cells in each of two rows that align in the same two columns — eliminate from those columns.
Rectangle patternRow-column eliminationFish technique
14
Lesson 14: Swordfish
⏱ 25 minThe three-row extension of X-Wing. A digit in 2–3 cells across three rows aligning in the same three columns.
Three-row fishColumn eliminationPattern recognition
15
Lesson 15: Coloring
⏱ 30 minUse alternating color chains to prove where a candidate must be placed based on logical exclusions and contradiction.
Alternating chainsColor contradictionCandidate inference
Mastering all five advanced lessons gives you the toolkit to consistently solve Expert Sudoku puzzles. When you are ready for the ultimate challenge, move on to the Expert level where Jellyfish, XY-Wing, and Alternating Inference Chains await.