Grafite Sudoku
Printable Hard Sudoku #2
28 given numbers, hard level. At some point you need techniques beyond singles: write pencil marks.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 8 | 1 | 6 | 9 | |||||
| 2 | 6 | 8 | 7 | ||||||
| 3 | 2 | 1 | |||||||
| 4 | 1 | 7 | 4 | ||||||
| 5 | 9 | 3 | 2 | 5 | |||||
| 6 | 6 | 8 | 7 | ||||||
| 7 | 3 | 1 | |||||||
| 8 | 5 | 1 | 9 | ||||||
| 9 | 5 | 9 | 2 | 6 |
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 | 7 | 3 | 8 | 1 | 2 | 6 | 4 | 9 | 5 |
| 2 | 5 | 4 | 6 | 8 | 7 | 9 | 1 | 2 | 3 |
| 3 | 2 | 1 | 9 | 4 | 3 | 5 | 7 | 6 | 8 |
| 4 | 1 | 2 | 7 | 5 | 6 | 8 | 3 | 4 | 9 |
| 5 | 8 | 9 | 3 | 7 | 1 | 4 | 2 | 5 | 6 |
| 6 | 4 | 6 | 5 | 2 | 9 | 3 | 8 | 1 | 7 |
| 7 | 9 | 8 | 2 | 6 | 4 | 7 | 5 | 3 | 1 |
| 8 | 6 | 7 | 4 | 3 | 5 | 1 | 9 | 8 | 2 |
| 9 | 3 | 5 | 1 | 9 | 8 | 2 | 6 | 7 | 4 |
Where to start
Look at row 4, column 7: only one number fits there.
The rules
Every row, every column and every 3×3 box must contain the numbers 1 to 9, each exactly once.
Tips for solving it
- Fill in candidates for the whole grid before hunting for techniques: with few clues you need all of them.
- Look for hidden pairs: two numbers that have only the same two spots in a row.
- If a number has only two spots in two rows, in the same two columns, that is an X-Wing: remove it from the rest of those columns.
- Take a break when you are stuck: the right step often shows up when you come back with fresh eyes.