文档介绍:++ +-
3 ×3÷ 3 ×3 25×7×4
8
a+ (b + c )= a+b+c a +(b-c)= a+b-ca –(b-c)= a-b+c a-( b +c)= a-b-c;
-(+) +(+)
-(+) 7 2 +( 5 - 2 )
17 18 17
5 6 -( 3 - 1 )
7 8 7
a×(b×c) = a×b×c, a×(b÷c) = a×b÷c,
a÷(b×c) = a÷b÷c , a÷(b÷c) = a÷b×c,
×( 8 ÷) ×( 4 × )
×( 213×) ÷(4÷100) ÷(71× 74 )
93 100
11 3 1 1 2 3 19 5
24 ( )
×(12 - 8 - 6 + 3 ) (12+ 7 ) ×7 7 5 - 20 × 38
16 7 3 7
×+× × - ×
5 13 5 139 9
×-× ×+×
5 5
9999+999+99+9 4821-998
××25 ×88