Killer Expert Sudoku

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Choose a number, and place it in the grid above.

 123456789
(Clear Possibilities)

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How to Play Expert Killer Sudoku

To solve Expert Killer Sudoku, fill in the grid using classic Sudoku rules along with extra cage constraints.

  • Every row, column, and 3x3 block must contain the numbers 1–9 exactly once.
  • The numbers inside each dotted cage must add up to the total shown in the top-left corner.
  • No number can repeat within a cage.
Expert killer sudoku grid showing the rules

Expert Killer Sudoku Strategies

Expert Killer Sudoku is the second hardest variant, just behind Evil Killer Sudoku. With few givens, you'll have to use logic and advanced candidate elimination techniques to solve the puzzle. Here are some proven techniques to help you place numbers with ease.

  • Start by solving small cages. Cages with one to three cells can often be solved quickly. One-cell cages are solved immediately (for example, H9 = 3). In a two-cell cage where one value is given, subtract it from the cage sum to find the other cell. For instance, if the cage total is 6 and G4 is 4, then H4 must be 2 (6 − 4 = 2).
  • Look for cages with limited candidate options. For example, cells E4, E5, and F5 make up a cage with the sum of 6. Because 3 is given, 1 and 2 are the only possible candidate combinations. There is a 1 in Column F, so F5 is 2 and E5 is 1.
  • Use conjugate pairs to narrow possibilities. A conjugate pair occurs when two cells in a unit can only hold the same two candidates, allowing you to eliminate those candidates from intersecting units. This is especially powerful when used with cage sums. For example, A5 and D5 can only be 4 or 5. The A5 and A6 cage must add to 7, with possible candidates of 1+6, 2+5, or 3+4. The pair 1+6 is ruled out because A5 must be 4 or 5, and 3+4 is ruled out because row 6 already contains 3. That leaves A5 = 5 and A6 = 2.
  • Use the Rule of 45. Every unit (row, column, or 3x3 block) contains the numbers 1–9, which add up to 45. You can combine this knowledge with cage sums to determine cell values. For example, in the top-right block, all cages except one are fully contained within the block. Adding their sums (23 + 16 + 8 + 3 = 50) and subtracting 45 (50 − 45 = 5) shows that the remaining cell, I4, must be 5.
Expert killer sudoku grid showing strategy examples

If Expert Killer Sudoku is too much of a challenge, we also offer three easier levels – Easy, Medium, and Hard.