The law of subtraction table is that the minuend is unchanged, and the minuend and the minuend increase at the same time. Other laws: if the minuend increases 1, the difference increases 1, and if the minuend remains unchanged, the difference decreases 1. Horizontal arrangement: 1 minus several, 2 minus several, 3 minus several, 10 minus several. Vertical arrangement: negative 1, negative 2, negative 3, negative 10.

China used the "99 formula" earlier. Sentences such as "3927", "684 18", "483 12" and "6636" can be found in books such as Xunzi, Guanzi, Huainanzi and Warring States Policy. It can be seen that as early as the Spring and Autumn Period and the Warring States Period, 99 multiplication songs became popular.

To sum up, longitudinal observation shows that the reduction is constant, and the gain 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.

There are the following rules:

1, observed vertically, it can be found that the reduction is constant, and the number changes with the change of the minuend.

2. Horizontal observation shows that the minuend is unchanged, and the smaller the minuend, the greater the number.

3. Obliquely observed, meiosis and meiosis become larger or smaller at the same time, and the number remains unchanged.

Subtraction is a mathematical operation that represents the operation of removing an object from a collection. Its symbol is the 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).

Subtraction follows several important patterns. It is anti-commutative, which means that changing the order will change the sign of the answer. It is not associative law, that is, when a subtraction exceeds two numbers, the order of subtraction is very important. Subtracting 0 does not change a number. Subtraction also follows predictable rules related to addition and multiplication.

These laws can be proved, starting with the subtraction of integers and summarizing them with real numbers and other things. Continue the general binary operation of these patterns and learn in abstract algebra.