Formula calculation is a recursive equation calculation, which is an operation to write out the calculation process completely, that is, vertical calculation. After studying vertical calculation, you will learn formulas that can be used for continuous calculation, such as mixed operation. When calculating mixed operations, it is generally to calculate a formula step by step (step by step, the original formula cannot be written with an equal sign), and the process of each step should be written out.
Generally speaking, the equal sign should go forward, not align with the first line, or leave the original calculation. The main thing to master is to remember to calculate multiplication and division first, and then add and subtract. In the continuous calculation of multiplication and division, it should be calculated from left to right. When you encounter parentheses, you must first calculate the inside of parentheses.
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, check whether the numbers and symbols copied from books to exercise books are correct; The second is to check whether the numbers and symbols copied from horizontal to vertical are correct; Third, it is necessary to check whether the draft is copied vertically, horizontally, and whether the decimal point position is correct or not.
Four operation sequences in disjoint calculation;
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 speaking, the order of these four operations is as follows:
1, sibling operations In an expression, if only sibling operations are included, operations should be performed from left to right. That is to say, only addition and subtraction, or only multiplication and division are mixed operations, and their operation order is calculated from left to right.
2. A pair of two-level operations: If an expression contains both first-level operations and second-level operations, then the second-level operations should be calculated first, and then the first-level operations should be calculated. That is, "multiply first and then divide, then add and subtract", or "multiply first and then divide, then add and subtract" for short.
3. Operation with brackets: If you want to change the operation order mentioned above, you need to use brackets. There are three kinds of brackets commonly used: parentheses, marked as (); Parentheses; Braces. When using the bracket, pull on both sides and add in the middle. Use parentheses first, then brackets, and finally braces.
If there are several kinds of parentheses in an expression, the multiplication or division in parentheses should be calculated first, then the addition or subtraction in parentheses, and finally the parentheses. When calculating, the formulas in brackets should be calculated in the order mentioned above, and then the results should be calculated in the order of numbers outside brackets.