期末复习‖五上数学小数乘法简便运算
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简介
一、乘法交换律 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 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、拆数+乘法结合律 0.125×8.8 =0.125×8×1.1 =1×1.1 =1.1 0.25×0.28 =0.25×4×0.07 =1×0.07 =0.07 0.125×3.2×2.5 =(0.125×8)×(0.4×2.5) =1×1 =1 四、乘法分配律 (1.25-0.125)×8 =1.25×8-0.125×8 =10-1 =9 (正用) (1.25+2.5)×0.8 =1.25×0.8+2.5×0.8 =1+2 =3 (正用) 3.72×3.5+6.28×3.5 =3.5×(3.72+6.28) =3.5×10 =35 (逆用)
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