This year saw the release of my unique take on KenKen(TM)/Calcu-doku puzzles: the book TomTom Puzzles. "Humanizing" calcu-doku puzzles, by creating more interesting puzzles to look at, as well as more interesting puzzles to solve, has been a real signature of my recent construction. I explored many types of visual themes for these puzzles, and one of the common ones not involving region shapes is having just one or two clue values repeated throughout the puzzle. For example, I made a 24/7 puzzle that was fit to be solved any time on any day, and a "Dirty Dozen" puzzle with exactly twelve 12s and no other clues.
Today's date is a really good one for making another themed challenge using just 12 and 24. This puzzle is a bit hard, but if no one has a walk-through posted in the comments by this weekend, I'll start putting up some hints to get started. Happy Puzzling!
Rules: Enter a digit from 1 to 8 into each cell so that no number repeats in any row or column. The number in the upper-left of each bolded cage must equal the value of a mathematical operation (+ or x) applied to all the digits in the cage. Digits can repeat in a cage, provided they don't repeat in a row/column.