More about Sudoku
Killer Sudoku
Killer Sudoku keeps the classic grid but swaps most of the given digits for cages that have a target sum. It plays like Sudoku mixed with arithmetic.
Killer Sudoku follows classic Sudoku rules and adds cages, groups of cells outlined with a small number in a corner. The digits in a cage must add up to that number, and no digit may repeat inside a cage. Few or no digits are given at the start.
The rules
- Fill the 9 by 9 grid so each row, column and 3 by 3 box contains 1 to 9 once, as in classic Sudoku.
- The grid is split into cages. The small number in a cage is the sum of its digits.
- A digit cannot repeat inside a cage.
Useful tricks
- Cage combinations. A two-cell cage with sum 3 can only be 1 and 2. A three-cell cage with sum 24 can only be 7, 8 and 9. Memorize the extremes.
- The 45 rule. Every row, column and box sums to 45. If cages fill a unit except one or two cells, subtract to find the missing sum.
- Combine with classic logic. Once you know a cage must hold certain digits, use pairs and hidden singles as usual.
Is it harder than Sudoku?
It is different. Early moves come from arithmetic rather than scanning, and you need good notes. The notes guide applies directly.
Killer Sudoku in the app
The Android app includes Killer Sudoku puzzles as part of the one-time Premium purchase. Each Killer puzzle is verified to have one solution that can be reached by logic.
Frequently asked questions
What is Killer Sudoku?
A Sudoku variant with cages that show a target sum for their digits.
Can digits repeat in a cage?
No.
Are there any starting digits?
Often none, or very few. The cage sums carry the information.