Killer Sudoku rules and puzzles

The case notes

Add two Killer cages to find their shared set

Combine two Killer cage totals to identify four digits, split them between the cages, then use a column clue to finish the deduction.

Put it into practice

Two cages share one row

A two-cell cage totalling 3 and a two-cell cage totalling 7 cover four different cells in the same row. Their combined total is 10. Because they share a row, all four digits must be different.

The minimum fixes the set

The smallest four distinct digits are 1, 2, 3 and 4. They total 10, so these are the four digits in the two cages. The 3 cage takes 1 and 2, leaving 3 and 4 for the 7 cage.

Place the digits

A 3 already in column four excludes 3 from the cage cell in that column. That cell is 4, and its cage partner is 3. The row relationship is essential: separate cages do not automatically forbid repeats between them.

Read the transcript

These are two separate Killer cages in one row. One sums to three; the other sums to seven. Neither clue alone tells us exactly where its digits go. Add the clues. Together, these four cells total ten. They all share a row, so they must be four different digits. The smallest four different Sudoku digits are one, two, three and four. They already add to ten. So these cages, taken together, use exactly that set. The three-cage takes one and two. That leaves three and four for the seven-cage. Adding both clues made the second cage’s choices clear. There is already a three further down column four. So this top cell cannot be three; it is four. Its cage partner is three.

Keep following the clues