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And addition, subtraction, multiplication and division. What is the most important, and then what is important.
Without parentheses, the operation order is multiplication and division first, then addition and subtraction. If there are brackets, count them first, and then count the outside.

Elementary arithmetic: multiply and divide first, then add and subtract. If there are brackets, calculate what is in the brackets first. In an expression, there are addition and subtraction, multiplication and division According to the operation order of elementary arithmetic, you should calculate multiplication and division first, and then add and subtract. So the answer is: multiplication, division, addition and subtraction.

Summary: in elementary arithmetic: 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 brackets, count them first. If there are squares, count them first.