Kakuro Revisited

Naked Single

A cell whose only remaining candidate is one digit takes that digit, whatever the runs want.

Level 1 Basics Technique 02

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Both runs through r2c3 leave only 1: Across 10 already holds a 9, and Down 15 already holds 3, 9 and 2. The candidate list has one entry, so the cell is decided.

key digits

Why it works

A cell belongs to an Across run and a Down run at the same time. If every other digit is already used in one of those runs, only one digit is left.

Candidates are the digits a cell can still hold. When the candidate list has one entry, the cell is solved.

How to spot it

  1. Look at the candidate list of an empty cell.
  2. Cross out every digit that already appears in its Across or Down run.
  3. If exactly one digit remains, write it in.

Practice it

Open the app, choose a level that uses this technique, and ask the coach for the next step. Every hint links back to this guide.