How to Play Killer Sudoku
Killer sudoku follows the rules of classic sudoku: each row, each column, and each box contains every digit exactly once, from 1 to 4 in a 4x4 grid, 1 to 6 in a 6x6 grid, and 1 to 9 in a 9x9 grid. Instead of given numbers, the grid is divided into cages, groups of cells outlined with dotted lines. The small number in the corner of each cage is the sum of the digits inside it, and a digit can never repeat within the same cage.
Each puzzle has exactly one solution, and it can be found by logic alone: no guessing is ever needed.
How does difficulty work in killer sudoku?
Difficulty grows with the size of the grid. A 4x4 grid uses only the digits 1 to 4 and a handful of cages, ideal for learning the rules. A 6x6 grid adds more digits and more combinations, and a 9x9 grid is the classic killer sudoku, with many cages and sums to combine.
Tips for solving killer sudoku
- Start with single-cell cages: their sum is the digit itself.
- Look for cages with only one possible combination, like a sum of 3 in two cells (1 and 2) or a sum of 4 in two cells (1 and 3).
- Remember the total of every row, column, and box: 10 in a 4x4 grid, 21 in a 6x6 grid, and 45 in a 9x9 grid.
- Use pencil marks to note the possible digits in each cell, and erase them as you go.