What a 4x4 sudoku is
A 4x4 sudoku is the smallest sudoku there is. The grid has four rows, four columns and four 2x2 boxes, and every one of them has to contain the digits 1, 2, 3 and 4 exactly once. Half of the sixteen squares are already filled in, so a child only ever has to place eight digits, and each one can be worked out from the digits already in that square’s row, column and box. That makes 4x4 the right place to learn what sudoku is: noticing which number is missing from a row, a column or a box. There is no arithmetic in it.
Every puzzle here is generated and checked by the same two solvers we use for the full-size grids. Each one has exactly one solution, and each one can be solved with nothing more than “this square can only be a 3”. We keep at least eight of the sixteen squares filled so there is always an obvious next move.
Who these are for
- Children from about four, as soon as they can recognise the digits 1 to 4. Many solve their first one with a parent reading the rule aloud.
- Kindergarten and early primary classrooms, as a five-minute warm-up or an early-finisher task. Six per page gives a whole lesson’s worth of practice on one sheet.
- Anyone who has never tried sudoku and wants to understand the rules before moving to 6x6 or 9x9.
- Teachers and parents who want to introduce the words row, column and box with something the child can finish.
How to teach a child to solve one
- Point at an empty square and ask: “Which numbers are already in this row?” Then the column, then the box. Whatever is left is the answer.
- Start with the row, column or box that has the most digits in it. When three of its four squares are filled, only one number is missing and the child gets a win straight away.
- Say the rule out loud every time: each row, each column and each box has 1, 2, 3 and 4, once each. By the third puzzle most children say it themselves.
- When a square has two possible numbers, leave it and find an easier one. On these puzzles there is always a square with just one answer.
A pencil with an eraser is kinder than a pen. Mistakes are part of it, and the answer page is there for the grown-up to check.
Printing tips
Six per page is the default and gives squares about 18 mm wide, big enough for a young child’s handwriting. Choose four per page for squares of about 21 mm, or two per page for 28 mm squares if your child is still learning to write digits. The answer key always prints as the last page, so you can keep it back. Press New puzzles for a fresh set at any time, or Download PDF to save the sheet.
The next step up
When 4x4 becomes easy, 6x6 sudoku adds two more digits and rectangular boxes without the leap to a full 9x9 grid. For classroom sets with a name and date line, use the sudoku worksheets page, which prints 4x4 as well.