Futoshiki

A Latin square puzzle with inequality constraints.

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The rules

How to play

  1. 01

    Fill the Latin square

    Futoshiki (Japanese for “not equal”) is played on an N×N grid. Fill every cell with a single digit from 1 to N.

  2. 02

    Unique rows

    Each row must contain every digit from 1 to N exactly once — the same digit can never repeat within a row.

  3. 03

    Unique columns

    Each column must also contain every digit exactly once, so no value is duplicated down any column.

  4. 04

    Read the signs

    A greater-than or less-than sign between two adjacent cells shows which neighbour holds the larger value: A < B means A is smaller than B.

  5. 05

    Satisfy every inequality

    A finished grid obeys all the inequality signs at once, alongside the row and column rules — every constraint holds simultaneously.

Play smarter

Six ways to read the signs

Chase the extremes

In a run like A < B < C < D < E on a 5×5, A is forced to 1 and E to 5. Chains of signs pin their endpoints.

Eliminate as you place

The moment a digit lands, strike it from every other cell in that row and column to narrow the field.

Squeeze the signs

A sign next to a known digit narrows its neighbour instantly: a cell reading 3 > ___ can only hold 1 or 2.

Find forced positions

When constraints leave a digit only one legal cell in a row or column, place it there without hesitation.

Cross the two rules

A candidate that survives both the Latin-square rule and the surrounding inequalities is often the only choice.

Pencil the candidates

Note the possible digits for tight cells so the right value reveals itself as rows, columns and signs resolve.

Watch & learn

Two minutes to mastery