{"id":605,"date":"2025-12-18T09:45:30","date_gmt":"2025-12-17T20:45:30","guid":{"rendered":"https:\/\/thesudoku.com\/blog\/?page_id=605"},"modified":"2026-08-20T16:34:32","modified_gmt":"2026-08-20T04:34:32","slug":"naked-quad","status":"publish","type":"page","link":"https:\/\/thesudoku.com\/blog\/naked-quad\/","title":{"rendered":"Naked Quad"},"content":{"rendered":"\n
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< <\/a>Back<\/a><\/p>\n<\/div>\n\n\n\n

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How to Master the Naked Quads Strategy in Sudoku<\/strong><\/h1>\n\n\n\n

When Pairs and Triples aren’t enough to break a stubborn deadlock in Hard and Expert puzzles, you need to look for larger candidate combinations. The Naked Quad technique<\/strong> is the largest subset elimination strategy in Sudoku. Pretty similar to the \u201cNaked Triple,\u201d but based on four candidates instead of three, so it\u2019s a bit harder to spot.<\/strong><\/p>\n\n\n\n

By identifying four interconnected cells that lock four specific digits, you can perform a massive cleanup of pencil notes across an entire row, column, or block.<\/p>\n\n\n\n

The Logic Behind a Naked Quad<\/strong><\/h2>\n\n\n\n

A Naked Quad occurs when four cells<\/strong> inside the same unit (row, column, or block) contain a total combination of no more than four unique candidate digits<\/strong>.<\/p>\n\n\n\n

Look at this example:<\/p>\n\n\n\n

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\"Naked<\/figure>\n\n\n\n
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The highlighted cells contain only values 2, 4, 6, and 8. <\/p>\n\n\n\n

Because four cells are strictly restricted to four unique numbers, those four cells are legally locked. Even if we don’t know the exact order of the numbers yet, we know with 100% certainty that 2, 4, 6, and 8 will be absorbed by these four spots.<\/p>\n\n\n\n

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\"Naked<\/figure>\n\n\n\n
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That means 2, 4, 6, and 8 can\u2019t appear in other cells of the unit and can be deleted.<\/p>\n\n\n\n

The Golden Rule of Quads (Variations)<\/strong><\/h2>\n\n\n\n

Just like with Naked Triples, all four cells do not<\/strong> need to contain all four digits. A cell in a Naked Quad can contain two, three, or four of the candidates.<\/p>\n\n\n\n

For example, a perfectly valid Naked Quad of (2, 4, 6 and 8) can look like this:<\/p>\n\n\n\n