The official rules:
- The digits 1 through 9 appear in each row and each column exactly once.
- Digits in each shaded region must add to the indicated sum (denoted by +) or multiply to the indicated product (denoted by *)--both mod 9.
- Squares with multiple colors contain a number that’s used in the sum/product for adjacent regions of each of those colors.
- Remember: numbers can repeat within a shaded region if that repetition doesn't violate the first rule.