Mathrax - Sudoku and Maths

Mathrax is a logic puzzle. The goal is to fill in each cell with numbers from 1 to N, where N is the size of the puzzle's side. No number may appear twice in any row or column. Circles with additional conditions may appear on intersections of lines inside the grid. - A number and a sign of mathematical operation (addition, subtraction, multiplication, division) - a number is a result of an operati…