Title: A Four Color Problem (original)
On the last sum puzzle, I had no inspiration for the title. This week's puzzle is the first sum puzzle I created. The second was published in MAA Focus; so consider this a two-for-one week.
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.
- Squares with multiple colors contain a number that’s used in the sum for adjacent regions of each of those colors.
- Remember: numbers can repeat within a shaded region if that doesn't violate the first rule.