All Tutorials/Naked Quad

Naked Quad

intermediate

Four cells sharing four candidates

A naked quad involves four cells in a house that contain only candidates from a set of four digits.

Understanding the Concept

Four cells collectively contain only four different candidates.

Like triples, not every cell needs all four candidates.

Various combinations possible: {1,2,3,4}, {1,2}, {3,4}, {1,3,4}, etc.

These four digits are locked to these four cells.

Eliminate these four candidates from all other cells in the house.

Naked quads are rare and hard to spot due to many subset combinations.

Examples

Naked Quad Example

Cells with {1,3}, {3,6}, {1,6,9}, {3,9} form a quad with digits {1,3,6,9}.

Pro Tips

  • Quads are rare - don't spend too much time hunting for them
  • Usually easier to find the complementary hidden pattern
  • In a house of 9 cells, a naked quad implies a hidden quint (5)
  • Computer solvers find these easily, humans struggle

Latest Sudoku Articles

Sudoku Englishסודוקו עבריתSudoku DeutschSudoku FrançaisSudoku EspañolСудоку Русскийसुडोकू हिंदी