Logic Masters Deutschland e.V.

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.

This puzzle is intended as an easy introduction to the constraint. Here are some harder ones:

Sums are products sudoku #2

Sums are products sudoku #3

You can solve this in Penpa or SudokuPad.