Su Doku

The numbers puzzle: a grid of nine rows by nine, split into nine boxes, with each containing nine squares.

How to play: To fill in the grid so that every row, every column, and every box contains the digits one to nine exactly once.

Daily Telegraph: http://www.sudoku.org.uk/
Daily Sudoku: http://www.griffiths-jones.co.uk/sudoku/
Sudoku.com: http://www.sudoku.com

Those in grey means they are the empty boxes you we have to fill in. Notice that every row and every column will have number one to nine, without repeating.