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Pair → bookends

Two alike together decide both neighbours.

Technique 1 of 7 · Updated 12 October 2026

What is the bookends technique in Binairo?

When two of the same animal sit side by side, both cells beside them are decided for you. The no-crowds rule is local: it only ever looks at three consecutive cells. That makes bookends the cheapest deduction on the board, and the one to scan for first on every new line.

Pip: Two owls together in this row. The cells beside them can't be owls — that would make three. Place both foxes, then look again: you've just made a fox pair.

Interactive example · 1 of 2 · tap the empty cells

Pip: Same idea, standing up. The cells above and below the two owls are foxes. Then count: three owls already, so the last cell is a fox.

Interactive example · 2 of 2 · tap the empty cells

How to spot it fast

Read each line in pairs. Whenever two neighbours match, check both outside cells. On a fresh board, sweep every row and then every column — most players read rows and forget that the same pair logic runs down every column.

Common mistake

Only bookending one side. A pair in the middle of a line has two neighbours, and both are decided.

Practise it

Unlimited puzzles let you drill any size. Other techniques: Gap fill · Count exhausted · Count pressure · Triple look-ahead · Links = and × · Chain reasoning · hard puzzles.

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