6
5
7
4
7
5
4
7
3
5
1
7
4
6
5
3
1
6
4
7
9
9
4
1
8
9
6
8
7
1
5
2
2
1
4
9
There are Sudoku World Championships held annually, with competitors from over 30 countries.
There are Sudoku World Championships held annually, with competitors from over 30 countries.
There are 6,670,903,752,021,072,936,960 valid completed Sudoku grids — that's 6.7 sextillion.
There are 6,670,903,752,021,072,936,960 valid completed Sudoku grids — that's 6.7 sextillion.