Sudoku

Sudoku puzzles are quite popular around these days.

At the beginning, I thought Sudoku requires participants to add numbers up, but I was wrong. It was not until this afternoon did I realize that it is a game of logic. The rule is simple, but the puzzles can be pretty complicated. It would be easier for you to just try one game on-line to get a clear picture: http://www.sudoku.com.

Well, since I have serious trouble dealing with numbers, the puzzles are too difficult for me.