Logic Masters Deutschland e.V.

Normal sudoku rules apply.

Mod-5 Counters: Circled digits indicate how many of the up to 9 cells surrounding the circle (including itself) have the same value modulo 5 as itself. E.g., a circled 2 would count how many of the surrounding digits are from the set {2, 7}. Not all such circles are necessarily given.

Play in the CTC App 🐸

Example for reference: