What is the simple operation of the second volume of mathematics in grade four?

Simple operation generally refers to simple calculation, which is characterized by changing from difficult to easy, from complex to simple, from slow to fast.

In the operation of numbers, there are four operations: addition (+), subtraction (-), multiplication (×) and division (). In order to calculate them more simply in mathematics, we call them simple calculations for short. There are the following simple calculations (see the product of common special numbers and simple calculation formula for details):

1, addition: additive commutative law, additive associative law, divisor.

2. Multiplication: multiplicative commutative law, multiplicative associative law, multiplicative distributive law and multiplicative distributive law variants (4).

3. Subtraction: the basic nature and divisor of subtraction.

4. Division: the basic nature of division and the nature of constant quotient.

A typical example of "simple operation":

1, the difficulty is simple:

2 10÷7÷6 1035-(497+235) 2 10÷(7×6)。

1 100÷25 2700÷25÷4 246-78+54。

2, the difficulty is medium:

355+260+ 140+245 98× 10 1 48× 125 645- 180-245。

38×99+38 3500÷ 14÷5 175×56+25×56 50×25×20×40。

3. More difficult:

199999+ 19999+ 1999+ 199+ 19。

999×778+333×666。