Logic Masters Deutschland e.V.

Normal Sudoku rules apply (each row, column, and given 3x3 box must contain the digits 1 to 9). Everything is mod 10. So a 6 might mean 6, or 16, or 26, etc.

The following variants are all subject to the mod 10 rule. Digits along an arrow must sum to the number in the circle - e.g. if a 4 is in the circle, the digits along the arrow might sum to 4, 14, 24, etc. Digits on either side of a black dot must have a ratio of 1:2 (one is double the other) - e.g. 6 can be paired with 2 (6x2=12), 3 (3x2=6), or 8 (8x2=16).

Link to sudokupad