PlaySudoku.us
Medium · Puzzle #490
5
8
7
1
2
5
4
2
3
1
6
5
4
2
4
6
3
2
8
8
1
9
4
6
3
6
8
2
1
5
8
4
3
8
4
2
6
Always update pencil marks immediately after placing a digit — stale marks cause almost all solving errors.
Always update pencil marks immediately after placing a digit — stale marks cause almost all solving errors.
The Times of London received so many reader letters about Sudoku in 2004 that they had to hire extra staff.
The Times of London received so many reader letters about Sudoku in 2004 that they had to hire extra staff.