The arithmetic of subtraction: subtraction combined with combination: one number subtracts two numbers continuously, and the last two numbers can be added first and then added.

Subtraction, formula: a-b-c=a-(b+c)

For example:12-1-3 =12-(1+3)

First, the significance of subtraction: the operation of subtracting one quantity from another is called subtraction.

Second, the essence of subtraction:

1, subtracting a number is equal to adding the reciprocal of this number. a-b=a+(-b)

2. Subtracting a number and adding a number is equal to subtracting the difference between two numbers. a-b+c=a-(b-c)

Extended data 1. Arithmetic of addition

1, additive commutative law

When two numbers are added, the positions of the addend are exchanged and the sum is unchanged. a+b=b+a

2. Additive associative law

Add three numbers, first add the first two numbers, or add the last two numbers first, and the sum remains the same. (a+b)+c=a+(b+c)

Second, the algorithm of multiplication

1, multiplication commutation law

When two numbers are multiplied, the position of the exchange factor remains unchanged. ab=ba

2. Multiplicative associative law

To multiply three numbers, you can multiply the first two numbers or the last two numbers first, and the product remains the same. C=a (BC)

Baidu Encyclopedia-Operating Rules