What a 6x6 sudoku is
A 6x6 sudoku has six rows, six columns and six boxes, and each of them must contain the digits 1 to 6 once. The boxes are rectangles, two rows by three columns, which is the one thing that surprises people coming from 9x9: a box shares its rows with one neighbour and its columns with two. Otherwise the rules are the same as any sudoku, and so is the logic. There are thirty-six squares, and on an easy puzzle at least eighteen of them are given.
6x6 is the step between the 4x4 grids young children start on and the full 9x9. It is small enough to finish in a few minutes, but large enough that you have to look at rows, columns and boxes together. It is also the size where hidden singles first become useful.
Two levels
Easy puzzles can be solved with naked singles only: at every point there is a square with just one possible digit, and at least 18 of the 36 squares are given. This is the right level for children who have done 4x4 and for anyone’s first week of sudoku.
Medium puzzles need hidden singles, and sometimes a pair or a box-line elimination. You look for where a digit can go in a row rather than what a square can be. At least 12 squares are given. Medium suits older children and adults who want a short puzzle with some thinking in it.
Both levels are graded by the techniques a solver needs, not by counting clues, and every puzzle is checked by two independent solvers to have exactly one solution.
Who these are for
- Children from about six or seven, at school or at home. Four per page is a comfortable homework sheet.
- Classrooms: a 6x6 fits a ten-minute slot, and six per page covers a group with one sheet.
- Adults who want a quick puzzle with a coffee rather than a half-hour 9x9.
How to solve a 6x6
- Start with the box or row that has the most digits. A box with four digits leaves only two squares to fill, and the rows will usually tell you which is which.
- For each empty square, cross out the digits already in its row, column and box. If one digit is left, write it in.
- On medium puzzles, pick a digit and scan a row: if it fits in only one square of that row, it goes there even if that square has other candidates. That is the hidden single, and it is the main new idea at this size.
- Remember that boxes are two rows tall and three columns wide. A digit in the top row of a box rules it out of the whole box and of that row right across the grid.
Printing tips
Four per page is the default, with squares about 14 mm wide. Choose two per page for larger squares of about 19 mm for younger solvers, or six per page for the most puzzles on one sheet, with squares of about 12 mm. The answer key prints last. Switch between Easy and Medium with the Difficulty control, and press New puzzles for a fresh set.
Related pages
Start with 4x4 sudoku for younger children, or move up to easy 9x9 sudoku when 6x6 medium feels comfortable. The sudoku worksheets page prints 6x6 with a name and date line and makes class sets.