五年级上册数学《小数乘法简便运算》7类
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简介
一、乘法交换律a×b×c=b×a×c 0.25×8.5×4 =0.25×4×8.5 =1×8.5 =8.5 12.5×0.96×0.8 =12.5×0.8×0.96 =10×0.96 =9.6 0.5×0.34×0.6 =0.5×0.6×0.34 =0.3×0.34 =0.102 二、乘法结合律a×b×c=a×(b×c) 4.36×12.5×8 =4.36×(12.5×8) =4.36×100 =436 0.95×0.25×4 =0.95×(0.25×4) =0.95×1 =0.95 0.75×50×0.4 =0.75×(50×0.4) =0.75×20 =15 三、乘法分配律 (a+b)×c=a×c+b×c或【(a-b)×c=a×c-b×c】 (1.25-0.125)×8 =1.25×8-0.125×8 =10-1 =9 (125+2.5)×0.8 =125×0.8+2.5×0.8 =1+1 =2 3.72×3.5+6.28×3.5 =3.5×(3.5+6.28) =3.5×10 =35
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