Pointing Pair

Level: first needed in Hard / Expert puzzles. In one line: Inside a box, a number is limited to one row or column, so it is removed from the rest of that line.

A Pointing Pair (or Pointing Triple) happens when, inside one box, all the possible places for a number lie in the same row or the same column. Whichever of those cells ends up holding the number, it will be in that line. So the number cannot appear anywhere else in that row or column, outside the box.

The cells in the box "point" along the line and clear the number from it. Pointing pairs do not place a number by themselves; they remove candidates, and that usually creates a new single somewhere else.

Example from a real puzzle

This position comes from an Extreme puzzle in Sudoku Arena, at the exact moment the Pointing Pair is the next logical move. Cells are named by row and column: R3C4 means row 3, column 4.

In box 7, 9 is confined to one row, so it can be removed from the rest of that line. Result: remove 9 from R9C8.

Play this puzzle and look for the move yourself. It's a practice game, so it doesn't count towards your stats.

How to spot it

1. Switch on notes, or at least note where one particular number can go in each box.
2. Find a box where that number fits in only two or three cells.
3. Check whether those cells share a row or a column.
4. If they do, remove the number from every other cell of that row or column, outside the box.

Tips

• It works the same with three cells in a line (a pointing triple).
• This is usually the first technique you need on Expert puzzles, so it is a good one to look for as soon as singles run out.

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