The mathematical subtraction table has the following rules: vertically, it can be found that the reduction is unchanged and the product number changes with the change of the minuend. Horizontally, the minuend is a constant, and the smaller the minuend, the greater the number. Obliquely observed, meiosis and meiosis become larger or smaller at the same time, and the number remains the same.

Subtraction is a mathematical operation, which means the operation of deleting an object from a set. Its symbol is minus sign (? )。 For example, in the picture on the right, there are five? Two apples, five apples, two were taken away, leaving three apples. So 5? 2=3。 Subtraction is to remove or reduce physical quantities and abstract quantities with different objects (including negative numbers, fractions, irrational numbers, vectors, decimals, functions and matrices).