Killer Sudoku: the sum sudoku
Killer Sudoku: a sudoku with no starting digits, split into cages that show their sum. Logic and mental math, one solution only.
Play Killer SudokuFree, zero ads, no sign-up, on mobile and desktop.
How to play
Each digit from 1 to 9 once per row, column and box. The cells of a dotted cage add up to its number, with no digit repeated inside the cage.
Example
A 3 × 3 mini-grid (digits 1 to 3): each colour is a cage and Σ gives its sum. The one-cell cage is 1, the cage of 3 can only be 1 + 2; each digit once per row and column.
Tips to get better
- Start from cages with only one combination: 3 in two cells = 1 + 2, 17 = 8 + 9, 6 in three cells = 1 + 2 + 3.
- A row, column or box always adds up to 45: a cell sticking out of a box can be found by difference.
- A digit never repeats inside a cage, even when it spans two boxes.
What this game trains
- Logical reasoning: deduce the solution from the rules, without guessing.
- Mental arithmetic: calculate in your head, fast and right.
Levels
Easy · Hard · Expert · Hardcore — each level has its own leaderboard.
Challenge your friends
At the end of a game, send your score as a link: your friend plays exactly the same puzzle and you compare your times. There is also a daily challenge and tournaments.