#2 - Mathrax Sudoku
Mathrax Sudoku Standard Sudoku rules apply. Some intersections are marked by a number and an operator in a circle. The number is the result of the operation, applied to both pairs of diagonally opposite cells. A question mark means that the result of the operation is not given and has to be determined as part of the puzzle. An E in a circle means that all four adjacent digits are even. An O in a circle means that all four adjacent digits are odd. Penpa link to solve online: https://git.io/JWN6x