The first one: the law of multiplication and distribution
The most commonly used method in simple calculation is multiplication and distribution law. Multiplication and division means ax(b+c)=axb+axc, where A, B and C are arbitrary real numbers.
The second type: multiplicative associative law
The multiplicative associative law is also a simple method, which is expressed by letters as (a×b)×c=a×(b×c). Its definition (method) is: multiply three numbers, first multiply the first two numbers, and then multiply the third number.
The third type: multiplicative commutative law
Multiplicative commutative law is used to exchange the positions of various numbers: a× b = b× a.
The fourth kind: additive commutative law.
Additive commutative law is used to exchange various numbers: a+b = b+a.
Fifth: the law of additive association
Additive associative law combined with regular term calculation: (a+b)+c=a+(b+c).
Example:
( 1)4.35+8.6+ 15.65+ 1.4
= 4.35+ 15.65+(8.6+ 1.4)
=30
(2) 19.32-5.56-3.44?
= 19.32-(5.56+3.44)
= 10.32
(3)37.6-(7.6+3.25)
=37.6-7.6-3.25
=26.75
(4)5.49+2.68-3.49?
=5.49-3.49+2.68
= 4.68
(5)6.27+3.83+ 1.73?
=6.27+ 1.73+3.83
= 1 1.83
(6)8.4+3.5-8.4+3.5
=8.4-8.4+3.5+3.5
=7