Box Brain Sudoku
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Easy · technique 4 of 18
Cage Combinations
Only some sets of digits add up to a cage's total.
A Killer sudoku technique.
How it works
A two-cell 3 can only be 1 + 2, and a two-cell 17 only 8 + 9. Totals with one way to make them pin down candidates.
A worked example
Cage combinations: the 4 empty cells of the 28-cage must sum to 24 with distinct digits, so the cell in row 4, column 2 cannot be 5.
- The cells that make the pattern
- Candidates it rules out
A real position from a puzzle in the app. Small digits are the candidates the step looks at; coloured digits are already solved.
Practise it in Box Brain Sudoku
The app teaches Cage Combinations on this same board, then hands you puzzles that need it. When you are stuck mid-game, a hint first points you to the right area, then names the technique and shows the move.