Killer Sudoku for Beginners: Rules and How to Play
Sudoku a Day Blog
If regular Sudoku is not challenging enough, Killer Sudoku might be exactly what you need. It adds arithmetic to logic—every puzzle is a fresh challenge.
What Is Killer Sudoku?
Killer Sudoku is a variant of standard Sudoku. The grid is the same: 9×9, divided into nine 3×3 boxes. The rules are similar, with one twist: there are no given numbers. Instead, the grid is divided into "cages"—groups of cells surrounded by dotted lines.
Each cage has a small number in the corner. That number is the sum of all the digits in that cage. For example, if a cage of two cells has a "9" in the corner, those two cells must add up to 9.
The Rules
1. Every row must contain the numbers 1-9 exactly once.
2. Every column must contain the numbers 1-9 exactly once.
3. Every 3×3 box must contain the numbers 1-9 exactly once.
4. Every cage must sum to the number shown in its corner.
5. No number can repeat within a cage.
How to Get Started
Start with the smallest cages. A cage of one cell always equals its sum—place that number immediately.
Look for cages that cover an entire row, column, or box. If a cage covers all nine cells in a row, the sum must be 45 (1+2+3+4+5+6+7+8+9=45).
Use the "45 rule": every row, column, and box must sum to 45. If you know eight of the numbers in a row, you can calculate the ninth.
Tips for Beginners
1. Pencil marks are essential. Write every possible number in every cell based on both the row/column/box constraints AND the cage sums.
2. The 1-9 sum is key. Remember that cages must follow the 1-9 rule within themselves—no repeats within a cage.
3. Start with 45. Look for opportunities to use the 45 rule on rows, columns, or boxes with known cage sums.
Try It Today
Killer Sudoku takes the logical satisfaction of regular Sudoku and adds an arithmetic challenge. It is harder, but also more rewarding.
Try our Killer Sudoku puzzles and see if you are ready for the challenge.