I. 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.
Second, the relationship
Multiplication is a simple operation of addition and division is a simple operation of subtraction.
Subtraction is the inverse of addition and division is the inverse of multiplication.
Appendix+Appendix = Sum
Negative-negative = difference
One addend = and-the other addend.
Subtraction = minuend-difference
Subtraction = difference+subtraction
Factor × factor = product
One factor = product ÷ another factor
Dividend = quotient
Divider = Divider
Dividend = quotient × divisor