6
2
1
9
6
3
8
5
7
5
2
1
9
7
6
8
9
9
4
6
1
2
5
4
9
6
8
1
5
5
7
4
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.