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简介:
一、乘法分配律
(1.25-0.125)×8 (125+2.5)×0.8 3.72×3.5+6.28×3.5
=1.25×8-0.125×8 =125×0.8+2.5×0.8 =3.5×(3.5+6.28)
=10-1 =1+1 =3.5×10
=9 (正用) =2 (正用) =35 (逆用)
二、乘法交换律
0.25×8.5×4 12.5×0.96×0.8 0.5×0.34×0.6
=0.25×4×8.5 =12.5×0.8×0.96 =0.5×0.6×0.34
=1×8.5 =10×0.96 =0.3×0.34
=8.5 =9.6 =0.102
三、乘法结合律
4.36×12.5×8 0.95×0.25×4 0.75×50×0.4
=4.36×(12.5×8) =0.95×(0.25×4) =0.75×(50×0.4)
=4.36×100 =0.95×1 =0.75×20
=436 =0.95 =15
四、拆数+乘法结合律
0.125×8.8 0.25×0.28 0.125×3.2×2.5
=0.125×8×1.1 =0.25×4×0.07 =(0.125×8)×(0.4×2.5)
=1×1.1 =1×0.07 =1×1
=1.1 =0.07 =1