Monkeymore Sudoku

Hidden Quad

Level 8 · Blue Belt

Prerequisite: Hidden SubsetsLearn next → Hidden Triple

Overview

A Hidden Quad is the four-cell extension of Hidden Pairs and Triples. When four candidates appear exclusively in four cells within a house, all other candidates can be eliminated from those cells.

How It Works

  1. Within a house, identify four digits that appear only within the same four cells.
  2. These four cells must contain these four digits.
  3. Eliminate all other candidates from these four cells.

Example

Check digits 2, 3, 6 and 9 in row 3.

1 / 25

Tips & Patterns

  • Hidden Quads are quite rare - don't spend too much time looking initially.
  • They often appear in puzzles designed to require advanced techniques.
  • Software or systematic checking helps identify them reliably.