The Fourth Room

sudoku is a great tool for keeping the wheels of the mind turning
6 8 9
5 7
7 8 6 2
2 7
x2 3 x1 9 1
7 8 2
6 1 5 3
x3 3
4 1 6


What is the value of 'x1' :


What is the value of 'x2' :


What is the value of 'x3' :



What country does Sudoku come from?