Current location - Training Enrollment Network - Mathematics courses - What is the essence of subtraction of the four operations of mathematics in the second volume of the fourth grade?
What is the essence of subtraction of the four operations of mathematics in the second volume of the fourth grade?
Basic arithmetic

Addition, subtraction, multiplication and division are called four operations.

Among them, addition and subtraction are called first-order operations, and multiplication and division are called second-order operations.

operation sequence

When there is only one level of operation, it is calculated from left to right;

When there are two levels of operation, multiply first and then divide, then add and subtract;

When there is a layer of brackets, count the brackets first;

When there are multiple parentheses, count the parentheses first.

If there is a square, count it first.