Killer Sudoku Puzzles

Killer Sudoku is a mix of Sudoku and Kakuro puzzles. Once again, the digits from 1 to 9 in every row, every column and every outlined 3 by 3 square should be different. However, there is one additional rule to be satisfied - the digits in every indicated area in the grid should add up to the number shown inside.

The Killer Sudokus below (sorted by difficulty) are shared by KrazyDad, a website with thousands of various types puzzle problems. For even more Killer Sudokus, visit www.krazydad.com.

Remark: All materials are copyrighted, for personal use only. If you want to use any of them for a book, app, website or periodical, please contact the authors first.