If the puzzle gets too frustrating (and it shouldn't), you could always poke a hole in the center and have it swirl around for a breath of fresh air.
The official rules:
- The digits 1 through 9 appear in each row and each column exactly once.
- Digits in each shaded region must multiply to the indicated product.
- Squares with multiple colors contain a number that’s used in the product for adjacent regions of each of those colors.
- Remember: numbers can repeat within a shaded region if that doesn't violate the first rule.