Do the same level of addition and subtraction, and calculate from left to right in turn.

When there are brackets in the formula, remember the brackets first.

If there is a plus sign before the brackets, it doesn't hurt to remove them.

If you subtract the symbol before the brackets, remove the brackets and make changes.

Parentheses are the sum of two numbers, and both numbers should be reduced.

In brackets is a minus b. If you want to subtract A, you should add B. ..

Check the number carefully to make sure it is not broken.

Simple formula of addition and subtraction mixed operation

The formula of addition and subtraction mixed operation should be calculated at the same level, from left to right in turn. When there are brackets in the formula, remember the brackets first. If there is a plus sign before the brackets, it doesn't hurt to remove them. If you subtract the symbol before the brackets, remove the brackets and make changes. Check the number carefully to make sure it is not broken.

Generally speaking, operation refers to algebraic operation, which is the correspondence in a set. For a pair of elements A and B taken out in sequence in set A, there is a unique third element C corresponding to it in set A, which is called an operation defined in set A. From this operation, two operations can be obtained, that is, one of A and B is expected and C is known. The operation thus obtained is called the inverse operation of the original operation.

Mixed oral arithmetic rules of addition, subtraction, multiplication and division

Addition and subtraction are called the first-level operation, and multiplication and division are called the second-level operation. In addition, subtraction, multiplication, division and elementary arithmetic, the second-level operation is calculated first, and then the first-level operation, that is, the multiplication and division method is calculated first, and then the addition and subtraction method is calculated. In order to avoid mistakes in the order of operations, we should first look at what operations are in the question, which step to calculate first, and then calculate with strokes, so as to ensure foolproof.