First, the guiding method
The simple operation of fractions is the same as that of integers and decimals, and the simple operation rules and properties of integers are also applicable to fractions and decimals. In the related calculation of scores, we should think of rounding.
Second, the basic operation law
1, additive commutative law: a+b = b+a.
Additive associative law: (a+b)+c=a+(b+c)
2. Multiplicative commutative law: a× b = b× a.
Law of multiplicative association: (a×b)c=a(b×c)
Multiplication and distribution law: (a+b)×c=a×c+b×c
3. Rules for removing brackets: put a plus sign (multiplication sign) in front of brackets, and remove the invariant sign of brackets.
The minus sign (division sign) precedes the brackets. When the brackets are removed, the symbol should be changed.
Third, special exercises
1. Use the addition algorithm for simple calculation (applicable to continuous addition formula)
( 1) 1/4+3/5+3/4
(2)2/3+2/5+ 1/3+3/5
2. Simple calculation by using multiplication commutative law and associative law (suitable for continuous multiplication formula)
( 1) 1/3×3/7×7/3
(2) 1/4×3/25×4
(3)3/26×5/7×39
3. Use the laws of multiplication and distribution for simple calculation (formulas applicable to multiplication and addition).
( 1)7/ 1 1×2/7+7/ 1 1+5/7
(2)3/8×4/9+5/9×3/8
(3)25×(3/5+ 1/25)
(4)3/7×6+3/7
(5)( 1/3+5/8)×24