Mathrax consists of a square grid. 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 be situated 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 operation execution with numbers in diagonally adjacent cells. A letter " E " ("even") - all numbers in four cells are even. A letter " O " ("odd") - all numbers in four cells are odd. The puzzle book contain: - 200 Puzzles - Handy 6 x 9 inch Book Layout - 2 Puzzles per Page - Ideal for Experts In the book you will find a description and examples of solutions for all puzzles. The book is for those who like logic and math problems. Decide, developing and improving.