Killer Sudoku - 200 Hard to Master Puzzles 9x9 (Volume 15)

Killer Sudoku (also known as "Sums Sudoku", "Sums Number Place", "Samunamupure", "Kikagaku Nampure") is a mathematical and logical puzzle. About Book
This book introduces you to the amazing world of Killer Sudoku puzzles.
It will help you understand the rules of this puzzle.
This book is perfect for players of all skill ages.
You will find 200 exciting puzzles, for professionals. HOW TO PLAY
Killer Sudoku is a mix of Sudoku and Kakuro.
Your goal is the same as in regular sudoku: fill every row, column and 3x3 region with the numbers 1-9 once.
Fill all rows, columns and 3x3 region with numbers exactly like in regular sudoku.
Every cell is a part of a cage, indicated by dotted line.
Make sure the cells can be added up to the sum of its cage.
Numbers cannot repeat within cage.
Numbers cannot repeat within a single row, column or 3x3 region. As Killer Sudoku belongs to the same class of puzzles as Sudoku the puzzle can demonstrate a wide spectrum of relative difficulty. The grade is determined by a combination of opportunities to solve at each stage and the difficulty of the strategy that grants each solution. Puzzles almost like Calcudoku, but unlike number cannot appear more than once in a block.