I came across this one while perusing puzzles by Clover from a few years ago. Semi-killer, she called it, and it should be easy. Instead of X in N digits, it’s X in N-1 digits. Only then there’s the question of any given digits. Are they in or out? Maybe it’s obvious, maybe it’s not.

Rules:
Normal Sudoku rules apply.
Semi-Killer: Digits within cages do not repeat, and the total in the top-left corner of the cage is the sum of all but one. The location and value of the digit not included in the total is not indicated.

Estimated difficulty: 2 out of 5

Solve on SudokuPad