Killer Sudoku (Los Angeles Times)

About Killer Sudoku (Los Angeles Times)

Killer sudoku keeps the rules of classic sudoku, with each digit from 1 to 9 once in every row, column and box, and adds a layer of arithmetic. The grid is split into cages, outlined groups of two or more squares, and each cage shows a small number: the sum its digits must make. No digit may repeat inside a cage. Most squares start empty, so the sums do the work that given digits do in an ordinary sudoku.

The Los Angeles Times publishes three killer sudokus every day on its free games page, at Easy, Medium and Hard, with a new set at midnight Eastern time. Each is the same for every player, and a picker keeps about two weeks of earlier puzzles at each level. The puzzles run on the Amuse Labs player in the browser with pencil marks and a timer, and an LA Times account adds streaks and records. The address once used for the paper's Impossible Sudoku now leads here.

It suits sudoku players who want more than the classic grid, and anyone who likes small sums: a cage of two squares adding to 3 can only be 1 and 2, and those certainties are where every solve begins.

How to play Killer Sudoku (Los Angeles Times)

1. Open Killer Sudoku on latimes.com/games and choose Easy, Medium or Hard.
2. Look at the cages: each dotted outline shows the sum its squares must add up to.
3. Fill the grid so each row, column and 3x3 box holds 1 to 9 once, and each cage adds up to its sum with no repeats.
4. Start with cages that have only one possible set of digits and pencil in candidates.
5. Finish the grid to stop the timer, or choose an earlier date to play a past puzzle.

Tips

• Learn the fixed combinations: two squares making 3 are 1 and 2, two making 17 are 8 and 9, three making 6 are 1, 2 and 3.
• Every row, column and box adds up to 45; subtract the cages inside one to find the leftover square.
• Work from the smallest and largest cage sums first, since they allow the fewest digits.

Questions