How to Use
- Set cells to how many squares the cage covers
- Enter the target sum shown in the cage's corner
- Toggle Whole box if the cage sits entirely within one 3×3 box — this doesn't change the digits (1–9 always apply) but is a useful reminder when cross-referencing box constraints
- Use Filter numbers to exclude digits already placed in the same row, column, or box
- Check Insights for digits that must or cannot appear in the cage
The 45 Rule
Every row, column, and 3×3 box always sums to 45. Enter the known cage sums within a row or column and the tool calculates the remaining sum for you — useful for finding hidden single cells or deducing cage totals.
Solving Strategies
- Start with cages that have only one combination — they're solved immediately
- Check Insights for numbers that appear in every combination — they must be in the cage
- Use Filter numbers to exclude digits placed in the same row, column, or box
- Use the 45-rule tool to work out unknown cage sums from known ones