1, each copy × number of copies = total number of copies, total number of copies/number of copies = number of copies, total number of copies/number of copies = number of copies.

2. Speed × time = distance, distance/speed = time, distance/time = speed.

3. Unit price × quantity = total price, total price/unit price = quantity, total price/quantity = unit price.

4. Work efficiency × working hours = total workload, total workload ÷ work efficiency = working hours, total workload ÷ working hours = work efficiency.

5. Appendix+Appendix = sum, and-one addend = another addend.

6. The minuend-subtrahend = difference, the minuend-difference = subtrahend, and the difference+subtrahend = minuend.

7, factor × factor = product, product ÷ one factor = another factor.

8. Divider = quotient, dividend = divisor, quotient × divisor = dividend.

Additive commutative law: A+B = B+A.

10, law of additive combination: (a+b)+c=a+(b+c).

1 1, multiplicative commutative law: ab=ba.

12, the law of multiplication and association: (ab)c=a(bc).

13, the distribution ratio of multiplication and addition: a(b+c)=ab+ac, a(b+c+d)=ab+ac+ad.

14, the nature of subtraction operation: a-(b+c)=a-b-c, a-(b-c) = a-b+c.

15. the nature of division operation: a÷(b×c)=a÷b÷c, a ÷ (b ÷ c) = a ÷ b× c