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Killer Sudoku Strategies
These are the steps the puzzles are graded with. Easy stays on singles. Medium adds a one-cell 45 or a pair. Hard and expert repeat the advanced steps instead of hiding a single trick at the end.
Beginner Cage combinations Some sums can only be made one way. Spot them first. Beginner The 45 rule Every row, column and box adds up to 45. Use it to find lone cells. Intermediate Innies and outies Cells poking in or out of a box give away their values. Intermediate Killer pairs Two cells that share the same two digits clean the rest of the house. Advanced Cage splitting Break big cages across boxes into sums you can solve. Advanced Hidden cages A sum you were not given can still behave like a cage. Beginner Singles When a cell has one digit left, or a digit has one home, write it in. Intermediate Locked candidates A digit trapped in one line of a box can be erased from the rest of the line.