The case notes
What an unnumbered cage means
A dashed cage without a printed total still cannot repeat a digit; it gives no sum. Watch a worked example, then try the idea in a puzzle.
Put it into practice
No clue means no sum
A dashed cage does not always have a number. Without a clue in its corner, it gives us no total to add.
The cage still forbids repeats
The cage still has a rule: its digits cannot repeat. This three is already inside, so no other cage cell can be three.
The cage reaches across the box edge
This lower cell is in another row, column and box from the given three. Ordinary Sudoku would not connect them; the cage does.
No total. Still no repeats.
If a cage has a total, use the sum and the no-repeat rule. If the total is absent, keep the no-repeat rule alone.
Read the transcript
A dashed cage does not always have a number. Without a clue in its corner, it gives us no total to add. The cage still has a rule: its digits cannot repeat. This three is already inside, so no other cage cell can be three. This lower cell is in another row, column and box from the given three. Ordinary Sudoku would not connect them; the cage does. If a cage has a total, use the sum and the no-repeat rule. If the total is absent, keep the no-repeat rule alone.
