Passion for Puzzles has a newly posted puzzle that was found on beer coaster in Belgium. The puzzle is a 10X10 grid with filled circles and open circles in various squares. The goal is to fill in more circles so that there are the same amount of filled circles and open circles in each row and column. I’ve only looked at the puzzle briefly, but it’s very interesting. I’m curious to know if it has a single unique solution. Also, if it can be solved purely by logic or requires trial and error.