Logic Masters Deutschland e.V.

The Rules:

1. [Sudoku] Normal sudoku rules apply -- fill every row, column and 3x3 box with the digits from 1 to 9 once each.
2. [Outside Clues] Clues outside the grid must be deduced -- they are simultaneously Sandwich clues, and Numbered Products clues.
   A ? could represent any one or two digit number.
   Square numbers are 1, 4, 9, 16, 25, 36... and primes are 2, 3, 5, 7, 11, 13....
   • [Sandwich] A sandwich clue is the sum of the digits in the cells between the 1 and 9 in that row or column.
   • [Numbered Products] A numbered product clue is the product of x and y, where x is the digit in the cell next to the clue, and y is the digit in the x-th cell in from the direction of the clue.
     example: the row 314592687 would have a 12 on the left or a 28 on the right.

The Puzzle:

Try it on Sven's SudokuPad