1, multiplication method of substitution: two numbers are multiplied, and the positions of two factors are exchanged, and the product remains unchanged. Expressed in letters: a× b = b× a.
2. Multiplication and association law: when three numbers are multiplied, the first two numbers are multiplied first, or the last two numbers are multiplied first, and the product remains unchanged. Expressed in letters: (a×b)×c=a×(b×c).
3. Multiplication and distribution law: the sum of two numbers is multiplied by one number. You can multiply them by this number first and then add them up. Expressed in letters: (a+b) × c = a× c+b× c.
Extended data:
1. Multiplication principle: If the dependent variable f is directly proportional to the independent variable X 1, X2, X3...Xn, and each independent variable is qualitatively different, if any independent variable f is missing, it will lose its meaning, then it is multiplication.
In probability theory, the result of an event needs to be divided into n steps, the first step 1 includes M 1 different results, the second step includes M2 different results, …, and the n step includes Mn different results. Then this event may have n = m 1× m2× m3×…× Mn different results.
2. addition principle: If the dependent variable F and the independent variable (z 1, z2, z3…,? Zn) is directly proportional to each other, and each independent variable has the same mass. If the dependent variable f still makes sense without any independent variables, it is addition.
In probability theory, if an event has n kinds of results, the first 1 result includes M 1 different results, the second result includes M2 different results, ... and these n kinds of results include Mn different results, then this event may have n = M 1+M2+M3+...+Mn different.