1, multiply first and then divide, then add and subtract. If there are brackets, count them first and then count them out. The operations at the same level are multiplication, division, addition and subtraction from left to right.

2. Addition, subtraction, multiplication and division are collectively called elementary arithmetic. Among them, addition and subtraction are called first-order operations; Multiplication and division are called secondary operations.

3, in the same level of operation, from left to right in turn.

4. Two-stage operation, first multiply and then divide, then add and subtract. When there are brackets, count the inside of the brackets first, and then the outside of the brackets.

5. When there are multiple brackets, count the brackets first, then the brackets inside, then the braces inside, and finally the brackets outside. If there is a power, calculate the power first. When performing mixed operations, the numbers in parentheses are calculated first, and the parentheses are from small to large. If there is a power, calculate the power first, and then from high to low.