Printable Killer Sudoku Puzzles

1. Numbers may only appear once in each row.
Killer Sudoku grids are similar to the regular Sudoku grids. We offer the 6 by 6 and the 9 by 9 versions. In the 6 by 6 grid, you have to fill in the numbers 1 to 6 each once in each row. In the example here you find 2 ones in the top row (in yellow), which is not allowed. The second 1 has to be a ............4 of course
2. Numbers may only appear once in each column.
In this 6 by 6 grid, we have 2 sixes in the last column and this is wrong. We need to fill in the numbers 1 to 6 once in each column. Which 6 is wrong? The 6 in the third position of course. But you figured that our already, because so far the rules are identical to Sudoku (you have to wait for rule number 4 to see the difference between the Killer and Regular puzzle.
3. Numbers may only appear once in each region.
Also in the Killer Sudoku puzzles the grids are divided in regions. The regions are clearly marked by thick black lines! In the 6 by 6 grids, we have 3 by 2 regions (3 times 2 equals 6 numbers) and with the 9 by 9 grid we have 3 by 3 regions (3 times 3 equals 9 numbers). In our example on the left we have 2 sixes (in green) in 1 region. And this is ......................WRONG! Can you figure out which 6 is wrong?
4. The sum of all numbers in a cage must match the small number printed in its corner.
Killer Sudoku grids are not only divided in regions but also in dotted cages. Each cage has a small number printed in it and the numbers you place in a cage must add up to that number (respecting rules 1, 2 and 3 of course). Cages are not confined to single regions and can be part of 2 regions like in our example on the left. The 4 numbers in the shaded cage must add up to 12 (and they do!) but are part of 2 different regions! Challenging, not?
5. You may not use the same numbers in a cage
In our example we have a cage clue number of 12 and a cage that is spread over 2 regions. Both threes in the cage are part of a different region and the total of 5, 3, 3 and 1 would add up to 12. This is, however, not allowed as no similar numbers may be used in a cage (nor region, row and column!). This example is there for showing a wrong solution.
Here you can find some helpful strategies to solve Killer math Sudoku puzzles:

Scan for the 2 digit cage clue numbers: 3, 4, 16 and 17
A great technique for solving Killer Sudoku is using the Kakuro number combinations. As no numbers may be repeated in a cage, the combination for the clue 3 must be 2+1, the clue 4 must be 3+1, the clue 16 must be 9+7 and for the 17 we need a 9+8. Scan your puzzles for these easy starting points. In our example we have put the 1 and 3 in the cage with the 4 clue. Be careful because the order could also be 3 and 1.

Scan for the 3 digit cage clue numbers: 6, 7, 23 and 24
When a cage consists of 3 digits, scan for a 6 clue (1+2+3), a 7 clue (1+2+4), a 23 (6+8+9) and a 24 (7+8+9). Just be careful in which order you place the numbers, as you have to respect the regular Sudoku rules.

4, 5, 6, 7 and even 8 digit cages
In case of a 4 digit case, scan for the numbers 10, 11, 29 and 30. When you encounter a 5 digit cage, look for 15, 16, 34 and 35. In case of a 6 digit cage you need to focus on the 21, 22, 38 and 39 and WHEN you have a 7 digit cage start with the 28, 29, 41 and 42. To make Killer Sudoku cages of 8 digit might sound cruel but they are ou there. Scan for the clue numbers 36 to 44 (all unique combinations)