First, the sum is -9, so the middle number is-1. Just fill in the two opposite corners of the difference 3 and 1 respectively, and the rest will be easy to fill in.

Positive number+positive number = sum of two numbers+A+B = A+B.

Negative number+negative number = sum of two numbers preceded by negative sign (-a)+(-b)=-(a+b).

Multiplying a negative number by a negative number is a positive number (-a)(-b)=ab.

Game introduction

"Rearrange the Nine Palaces" means "Rearrange Nine palace map". This is based on the popular mathematical game "Vertical and Horizontal Diagram" (also called "Rubik's Cube" or "Rubik's Cube Array"). The origin of Jiugong Game can be traced back to the "Hutuluo Book" in China's ancient mythology and history. Luoshu is the most basic 3×3 Rubik's cube array and the third-order Rubik's cube in mathematics. There are many vertical and horizontal diagrams in the mathematics books of Tang and Song Dynasties, and on this basis, the game of rearranging the nine palaces has emerged.