IntermediatePractice
Practise: Innies and outies
This Killer puzzle stalls at exactly the point where Innies and outies is needed. Work it out yourself, or jump straight to that position.
Skip the obvious cells and start where the technique matters.
Practice
Mistakes0Hints0Score2,000Time0:00
Your turn first
Spot the idea before the hint explains it
- 1. Look
- 2. Check
- 3. Proof
Look at the marked starting cell, cage outline and sum. Which digit or combination is forced, and what visible sum fact supports your idea?
How to spot it
Look for units where one or two cells belong to cages that mostly sit elsewhere. Single innies and single outies are the strongest: their digit follows immediately.
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Put it to use
Where you will meet it
Hard grids are built around moves like this one. That is where it earns its keep.
Play HardStuck on a grid of your own?
Type the position into the solver and it walks the whole solution, naming the technique behind every step — including this one.
Open the solver