Hidden Pair
Prerequisites: Naked Pair
Overview
A Hidden Pair is two digits that fit in only two cells of a house. Those two cells must hold those two digits, so every other candidate in them can go.
How It Works
In one row, column or box, two digits can each go only in the same two cells. Each digit needs a cell, and there are just two cells for the two digits, so one cell takes each. Any other candidate in those two cells is wrong. Every hidden subset has a naked mirror image in the same house: the house's other empty cells hold only the remaining digits. The hidden side is often the smaller one, so it is easier to spot.
When To Use It
Try it when you can't find a Naked Pair. The pair is hidden because extra candidates in its two cells cover it up.
How To Detect It
Go through a house one digit at a time and note where each digit can go. When two digits fit in the same two cells and nowhere else, remove every other candidate from those two cells.
Visual Example
Step 1 of 9
Two Digits, Two Cells
A Hidden Pair is two digits that fit in only two cells of a house. Those two cells must hold those two digits, so any other candidates in them can go.
Candidates already ruled out by earlier techniques aren't shown.
Practice
Your goal: fill the highlighted cell. Select a cell, then pick a number.
A Hidden Pair is hiding here. Find two digits that fit in only two cells of a house, clear the other candidates from those cells, then fill the Hidden Single.Candidates already ruled out by earlier techniques aren't shown.
Use it in a real game
Advanced puzzles are where these techniques start to matter.
Play an Advanced puzzle