Out-of-step calculation, that is, recursive equation calculation, has a class of problems that need to be calculated by recursive equations called out-of-step calculation problems. Every row of calculation results must be preceded by an equal sign. You must operate from left to right according to the rule of "multiply first, then divide, then add and subtract", and count the numbers in parentheses, brackets and braces first. Various algorithms can be used to make its calculation simpler and more accurate.

That is to say, leaving the original calculation:

For example:

35+65+98

How to calculate the formula = 100+98 = 198?

How to calculate the distortion? The main thing to master is to remember to calculate multiplication and division first, and then add and subtract. In the successive calculation of multiplication and division, it should be calculated from left to right. In the process of separation, the operation sequence line should be drawn according to the operation sequence, and the "three checks" should be done well. First of all, check whether the numbers and symbols copied from books to exercise books are correct. Second, check whether the numbers and symbols copied from horizontal to vertical are copied correctly. Third, check whether the draft is copied correctly in the vertical and horizontal directions, and whether there are any omissions.

[Edit this paragraph] Four operation sequences

Among the four operations, addition and subtraction are called primary operations, and multiplication and division are called secondary operations. Expressions that contain two or more operations are usually called mixed operations. The mixed operation of addition, subtraction, multiplication and division is also called elementary arithmetic. In elementary arithmetic, the prescribed calculation order is called operation order. Mathematically, the four operation sequences are as follows:

(1) Operation at the same level In an expression, if only the operation at the same level is involved, the operation should be carried out from left to right. That is to say, from left to right, only addition and subtraction operations are calculated, or only multiplication and division mixed operations are calculated.

(2) One-to-two operation

In an expression, if there are both first-level operations and second-level operations, then the second-level operations should be calculated first, that is, "multiply and divide first, then add and subtract", or "multiply and divide first, then add and subtract" for short.

(3) Operation with brackets

If you want to change the order of the operations mentioned above, you need to use parentheses. There are three kinds of brackets commonly used: parentheses, marked as (); Parentheses, marked []; Braces, marked {}. When using parentheses, use parentheses first, then brackets, and finally braces.

If a formula contains several brackets, it should be counted in brackets first, then in brackets, and finally in braces. When calculating, the formulas in brackets should be calculated in the order mentioned above, and then the results and the numbers outside brackets should be calculated in the same order.