Grafite Sudoku
Printable X-Sudoku #4
29 given numbers, medium level. At some point you need techniques beyond singles: write pencil marks.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 8 | 9 | 5 | ||||||
| 2 | 7 | 8 | |||||||
| 3 | 1 | 5 | 3 | ||||||
| 4 | 6 | 3 | 1 | ||||||
| 5 | 5 | 7 | 3 | 9 | 1 | 2 | 8 | ||
| 6 | 7 | 2 | 9 | ||||||
| 7 | 3 | 8 | 4 | ||||||
| 8 | 2 | 6 | |||||||
| 9 | 9 | 5 | 3 |
Print on A4 or Letter paper without resizing. The solution is on page 2.
Show the solution
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 3 | 8 | 9 | 5 | 1 | 7 | 2 | 4 | 6 |
| 2 | 2 | 6 | 7 | 9 | 4 | 8 | 3 | 5 | 1 |
| 3 | 1 | 5 | 4 | 3 | 6 | 2 | 8 | 9 | 7 |
| 4 | 9 | 2 | 6 | 8 | 3 | 1 | 4 | 7 | 5 |
| 5 | 5 | 7 | 3 | 4 | 9 | 6 | 1 | 2 | 8 |
| 6 | 8 | 4 | 1 | 7 | 2 | 5 | 9 | 6 | 3 |
| 7 | 6 | 9 | 2 | 1 | 5 | 3 | 7 | 8 | 4 |
| 8 | 7 | 3 | 5 | 2 | 8 | 4 | 6 | 1 | 9 |
| 9 | 4 | 1 | 8 | 6 | 7 | 9 | 5 | 3 | 2 |
Where to start
In row 3, the 8 has only one possible spot.
The rules
As in classic sudoku, every row, column and 3×3 box contains 1 to 9. On top of that, both shaded diagonals must also contain 1 to 9.
Tips for solving it
- Start from the center cell: it belongs to a row, a column, a box and both diagonals.
- Treat each diagonal like an extra row: which numbers are missing?
- Cells where the diagonals cross the corner of a box have many constraints: check them first.
- When you write a number on a diagonal, remove it from the pencil marks of the whole diagonal.