Prorus

Title: Prorus

Rating: 3/5

Not your typical product puzzle this week.  The board is what I call a "toral board," so named because the board is meant to be viewed not as a big square, but as what's called a fundamental region.  In this case, imagine folding the sides of the square together to get a cylinder.  Then fold the ends of the cylinder together, and you get what's called a torus (a donut, if you will).  Those associations (between left and right, between top and bottom, and, hence, between all corners) are reflected in the rules below.

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. 
• The board is a “toral board,” that is, cells at the end of one row are considered adjacent to those at the beginning of the same row; cells at the end of one column are considered adjacent to those at the beginning of the same column, and all corner cells are considered adjacent.