Normal sudoku rules apply: Fill the grid with digits from 1 to 9, so that every row, column, and 3x3 box contains each of the 9 digits exactly once.
Dotted lines define some cages within the grid. Digits may not repeat within a cage. Whenever two cages share an edge, the sum of the digits in one of the cages equals the product of the digits in the other. For example, a cage containing 1, 3, and 6 might share an edge with one containing 2 and 5, since 1+3+6 = 2*5. Cages which meet only at a corner are not restricted in this way.
I think this is slightly harder than Sums are products sudoku #1.
Solution code: Row 1.
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