1. Each row and each column must contain the numbers 1 through 4 (easy) and 1 through 6 (challenging) 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 numbers in the top-left corner.