How is Killer Sudoku different from regular Sudoku?
It adds cage sum constraints and usually provides fewer starting digits.
Can digits repeat in a cage?
No, each cage contains unique digits.
What is the 45 rule?
Since each row, column, and box must sum to 45, you can derive missing cells by subtracting known cage sums.
Is Killer Sudoku harder?
It requires both logic and arithmetic, so it is generally considered harder.
Do I need advanced math?
Only addition and subtraction up to 45.
