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简介:
运算定律 用字母表示
加法交换律 a+b=b+a
加法结合律 a+b+c=a+(b+c)
减法的性质 a-b-c=a-(b+c)
乘法交换律 a×b=b×a
乘法结合律 a×b×c=a×(b×c)
乘法分配律 a×(b+c)=a×b+a×c
除法的性质 a÷b÷c=a÷(b×c) (b、c≠0)
17.2+69+2.8
=17.2+2.8+69
=20+69
=89
265×105-265×5
=265×(105-5)
=265×100
=26500
4000÷125÷8
=4000÷(125×8)
=4000÷1000
=4
35-15.3-4.7
=35-(15.3+4.7)
=35-20
=15
25.8+7.5+2.5
=25.8+(7.5+2.5)
=25.8+10
=35.8
25×44
=25×4×11
=100×11
=1100
25×44
=25×(40+4)
=25×40+25×4
=1000+100
=1100
99×83+83
=99×83+83×1
=83×(99+1)
=83×100
=8300
101×87
=(100+1)×87
=100×87+1×87
=8700+87
=8787