1.  Each row and each column must contain the numbers 1 through 4 (when there are four columns/rows) or 1 through 6 (when there are six columns/rows) without repeating.

2.  The numbers within the heavily outlined boxes, called cages, must combine using the given operation (in any order) to produce the target numbers in the top-left corners.

3.  Freebies:  Fill in single-box cages with the number in the top-left corner.