Killer Sudoku, Difficulty 7

Puzzle 646 Aug 1 August 2009
Puzzle 648 Aug 2 August 2009
Puzzle 652 Aug 3 August 2009
Puzzle 658 Aug 5 August 2009
Puzzle 662 Aug 6 August 2009
Puzzle 680 Aug 12 August 2009
Puzzle 707 Aug 21 August 2009
Puzzle 719 Aug 25 August 2009
Puzzle 728 Aug 28 August 2009
Puzzle 743 Sep 2 September 2009
Daily Killer Sudoku