How to solve a 6×6 mini sudoku

A 6×6 sudoku uses the digits 1–6. Every row, every column and every 2-row by 3-column box must contain each digit exactly once. It is the sweet spot between a trivial 4×4 and a full 9×9: real deduction, five minutes. Digits publishes one every day, with 4×4 and 9×9 in unlimited mode.

1. Think in bands

The 6×6 grid has three horizontal bands of two boxes each. If a digit appears in one box of a band, it must appear in the other box of that band, in the row it has not used yet. That leaves at most three cells, and after checking the columns, usually one.

2. Scan digit by digit

Pick a digit that already appears several times. For each band and each column stack where it is missing, ask: which cells are still allowed? A cell is blocked if its row, column or box already has the digit. When only one cell remains, write it. Cycle through 1–6, then start again; each placement unlocks others.

3. Count the missing ones

A row, column or box with one empty cell has one option. With two empty cells, check which of the two missing digits is blocked in each cell by the crossing line; often only one arrangement works.

4. Single candidates

If everything else fails, look at one empty cell and list the digits not yet in its row, column or box. If only one digit survives, it goes there. Every Digits puzzle is generated so that these four steps are enough: givens are removed only while a solver still finds exactly one solution.

Keyboard and touch

Select a cell, then tap a digit on the keypad or type it; 0, Backspace or ⌫ clears; arrow keys move. Conflicting digits turn red immediately.

Going bigger

• 4×4 (2×2 boxes): a warm-up; two scans finish it.
• 9×9 (3×3 boxes): the classic; the same techniques apply, with pairs and “pointing” patterns for harder grids.

Related puzzles

Pixel (nonograms), Regions (star battle), Duo (binary) and Trail (path) round out the daily set.