8
4
2
9
3
1
6
1
2
3
7
5
8
5
3
9
7
2
3
4
3
9
6
2
8
4
7
1
7
9
3
4
6
1
8
5
7
At peak Sudoku popularity in 2006, over 600 different Sudoku books were published in a single year.
At peak Sudoku popularity in 2006, over 600 different Sudoku books were published in a single year.
At peak Sudoku popularity in 2006, over 600 different Sudoku books were published in a single year.
At peak Sudoku popularity in 2006, over 600 different Sudoku books were published in a single year.