Real number system is a set of mathematical objects, called real numbers, which is the basic principle and rule we adopt to obtain mathematical life. This situation is somewhat similar to games, such as chess. Chess system is a set of rules of the game, and the principles used to define the allowed movement modes also exist in it.

Our working experience in numbering provides us with all the familiar real number principles. But it is common to build consensus and avoid some mistakes. We should clarify the situation and explain these principles.

Real number systems, including the numbers -27 -2, 2/3…, are positive numbers that deserve our attention, such as 1/2, 1, sometimes expressed as +( 1/2),+1. The plus sign means "+",not addition, but a part of the symbol system. Similarly, "-"is used to represent such numbers (1/2), and 1- is part of the symbolic meaning of these numbers.