Writing a lot of puzzles in any one style invariably leads to a lot of ideas for variations in that genre. Here is another variation on calcudoku puzzles that won't fit into my current big project but works fine as a Friday Puzzle here.
Rules: Fill in the grid so that in each row and column the digits 1 through 6 appear once each. While the operations remain in the grid, the numeric values have "fallen" out of the grid and appear below. You will need to figure out where those numbers used to be before you can finish the puzzle.