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
Question 1:
1、25×(4×9)
=25×4×9 (multiplicative associative law)
= 100×9
=900
2、4×9×25
=9×(4×25) (multiplicative commutative law and multiplicative associative law)
=9× 100
=900
Question 2:
23×( 10+3)
= 23× 10+23×3
=230+69
=299
Question 3:
125×32
= 125×8×4
= 1000×4
=4000