KNS Puzzles offers the Killer Sudoku puzzles in the following formats:
Level 1 - Level 2 - Level 3 - Level 4
Complete the grid such that every row, every column, and every 3 x 3 block contains the digits from 1 to 9. Every cage has a little clue in the corner, and digits in each cage must add to the clue. A digit can't appear more than once in a cage. Normal Sudoku rules, tips, tricks and techniques apply. Sudoku help page for tips and hints. Pencil marks are the easiest way of keeping track of possible values for each square. Here we see the cage clue of 16, which can only be 7+9 or 9+7 (it can't be 8+8), so we enter both digits into the squares.
The puzzle is broken down into cages, and the small number in the corner tells you the sum of the digits in a cage, 15 = 1 + 5 + 9.
This is the start of a section of a puzzle.
A 4 cage can only be solved using 1 + 3 (as 2 + 2 isn't allowed).
There are 4 cages entirely in the 3x3 block, and these 4 cages add to 4 + 10 + 15 + 14 = 43. We know that all nine squares of a block add to 45, therefore this square is <2>. The other square in the 5 cage is therefore <3>.
These squares can't be 1 + 9 (because the <1> belongs to the 4 cage), 2 + 8 or 3 + 7 (because of the 5 cage). Therefore these squares are 4 + 6.
These squares can't be 6 + 9 (because of the 15 cage), and are therefore 7 + 8.
Therefore these square are 5 + 9.
This section will hopefully help with the rest of the puzzle.