Techniques · killer sudoku

Virtual Cages

The 45 rule can also give the total of a small group of cells (the innies or outies of a row, column or box). That group then works like an extra cage.

In the walkthroughs, every Virtual Cages step shades the cells of the pattern and names the cell and digit it proves, so you can see the move on the grid rather than read about it. Press “Skip to next hard step” to jump straight to it.

None of the walkthroughs published so far needs this one; it is here for completeness.

Where it sits

See the whole ladder on hard killer sudoku techniques, or look a puzzle up by number under solutions.