Skip to content
VEYRAPLAYPlay
Module 4 · IntermediateLesson 16 of 28

Hidden Pairs

Find two digits that are restricted to the same two cells in a unit and remove all other candidates from those cells.

Outcome

You can follow candidate positions across one unit, find two digits restricted to the same two cells, and remove the extra candidates hiding the pair.

Intro copy

Naked Pair:

Look at the cells.

Hidden Pair:

Follow the digits.

The reservation is the same. The discovery direction changes.

Step 1 — Hide the pair in noise

Show a row with several candidate-rich cells.

Highlight digit 4.

Only cells B and F contain 4.

Highlight digit 9.

Only cells B and F contain 9.

Prompt:

What do 4 and 9 have in common?

Expected:

They have the same two possible cells.

Fade every other candidate in B and F.

Prompt:

Which notes can be removed?

Learner cleans the cells to {4,9}.

Step 2 — Guided column Pair

Required state: Digits 3 and 8 appear only in the same two cells of a column; both cells contain several extras.

Prompt sequence:

  1. inspect candidate 3 positions;
  2. inspect candidate 8 positions;
  3. select the shared cells;
  4. remove all non-3/8 candidates from those cells.

Correct feedback:

Good. The column needs both 3 and 8, and these are their only two homes.

Step 3 — Find the pair without pre-highlighting cells

Only candidate filters are available.

Prompt:

Which two digits are running out of places in this box?

Learner decides which digits to inspect.

This trains the actual search behavior rather than only the cleanup.

Step 4 — False Hidden Pair

Show:

  • digit 2 appears in A/B;
  • digit 7 appears in B/C.

Prompt:

Do 2 and 7 form a Hidden Pair?

Correct: No.

Feedback:

Each digit may have two positions, but the position sets are different.

Step 5 — Convert the viewpoint

After cleaning a Hidden Pair, show:

{4,9} {4,9}

Prompt:

What would we call this structure if we discovered it by looking at the cells?

Correct:

Naked Pair.

The goal is to unify subset logic rather than store two unrelated pattern names.

Practice

Mix:

  • row;
  • column;
  • box;
  • deeply hidden pair;
  • false same-count/different-position pair.

Hint ladder

  1. “Stop looking for small cells.”
  2. “Which digits have only two positions in this unit?”
  3. “Compare those position pairs.”
  4. “Two digits share the same two cells.”
  5. Highlight extra candidates to remove.

Completion

Four Hidden Pairs plus two false-pattern classifications.

Next

Triples

Scale the same reservation from 2 digits / 2 cells to 3 digits / 3 cells.

Reference

Read Hidden Pair for the full digit-first search method and relationship to Hidden Singles.