The distribution rate of multiplication in the second volume of the fourth grade is: the result of multiplication of two numbers is the same, which is equivalent to multiplying two addends by this number respectively, and then adding the two products, the result is the same as that obtained without simple calculation.

When the sum of two numbers is multiplied by a number, you can multiply this number separately and then add it. This is the so-called law of multiplication and division.

Letter representation of the laws of multiplication and distribution;

(a+b)c=ac+bc .

There is another form of expression:

a(b+c)=ab+ac .

On the law of multiplication;

1, multiplication commutation law

When two numbers are multiplied, the position of the exchange factor remains unchanged. a×b=b×a .

2. Multiplicative associative law

To multiply three numbers, you can multiply the first two numbers or the last two numbers first, and the product remains the same. (a×b)×c=a×(b×c).

3. Distribution law

The main formula is (a+b) × c = a× c+b× c. When the sum of two numbers is multiplied by a number, you can multiply it first and then add it, and the product remains unchanged. This is the so-called law of multiplication and division.