Only the mixed operation of addition and subtraction should be calculated from left to right, and only the mixed operation of multiplication and division is the same. If there are both addition and subtraction and multiplication and division, calculate the multiplication and division first, and then add and subtract. If there are parentheses, the order of operations in parentheses should also be calculated first.
definition
Addition: the operation of combining two numbers into one number.
Subtraction: when two addends and one of them are known, the operation of finding the other addend.
Multiplication: the operation of finding the product of two numbers.
(1) Multiplying a number with an integer is a simple operation, and you can find the sum of several identical addends.
(2) Multiply a number by a decimal to find a few tenths, a few percent and a few thousandths of this number.
(3) A number multiplied by a fraction is a fraction of this number.
Division: the operation of finding another factor by knowing the product of two factors and one of them.