五年级上册数学《小数乘法》简便运算计算题

五年级上册数学《小数乘法》简便运算一、乘法交换律0.25×8.5×4＝0.25×4×8.5＝1×8.5＝8.512.5×0.96×0.8＝12.5×0.8×0.96＝10×0.96＝9.6二、乘法结合律4.36×12.5×8＝4.36×（12.5×8）＝4.36×100＝4360.95×0.25×4＝0.95×（0.25×4）＝0.95×1＝0.95三、拆数+乘法结合律0.125×8.8＝0.125×8×1.1＝1×1.1＝1.10.25×0.28＝0.25×4×0.07＝1×0.07＝0.07四、乘法分配律（1.25+2.5）×0.8＝1.25×0.8+2.5×08＝1+2＝3（正用）3.72×3.5+6.28×3.5＝35×（3.72+6.28）＝3.5×10＝35（逆用）五年级上册数学《小数乘法》简便运算五、把其中一个因数分成两个数的和或差,再按乘法分配律0.8×100.1＝0.8×（100+0.1）＝0.8×100+08×0.1＝80+0.08＝80.083.65×10.1＝3.65×（10+0.1）＝3.65×10+3.65×0.1＝36.5+0.365＝36.8650.32×403＝0.32×（400+3）＝0.32×400+0.32×3＝128+0.96＝128.964.6×0.9＝4.6×（1-0.1）＝4.6×1-4.6×0.1＝4.6-0.46＝4.140.85×199＝0.85×（200-1）＝0.85×200-0.85×1＝170-0.83＝169.150.79×99＝0.79×（100-1）＝0.79×100-0.79×1＝79-0.79＝78.2110.1×87＝（10＋0.1）×87＝10×87＋0.1×87＝870＋8.7＝878.77.5×102＝7.5×（100＋2）＝7.5×100＋7.5×2＝750＋15＝765五年级上册数学《小数乘法》简便运算六、添加因数"1"56.5×99+56.5＝56.5×99+56.5×1＝56.5×（99+1）＝56.5×100＝56509.7×99+9.7＝9.7×99+9.7×1＝9.7×（99+1）＝9.7×100＝9701.87×9.9+0.187＝1.87×9.9+1.87×0.1＝1.87×（9.9+0.1）＝1.87×10＝18.74.2×99+4.2＝4.2×99+4.2×1＝4.2×（99+1）＝4.2×100＝42012.7×9.9+1.27＝1.27×99+1.27×1＝1.27×（99+1）＝1.27×100＝1275.4×11-5.4＝5.4×11-5.4×1＝5.4×（11-1）＝5.4×10＝549.87×99＋9.87＝9.87×99＋9.87×1＝9.87×（99＋1）＝9.87×100＝98728.4×99＋28.4＝28.4×99＋28.4×1＝28.4×（99＋1）＝28.4×100＝2840五年级上册数学《小数乘法》简便运算七、更改因数的小数点位置6.66×3.3+0.666×67＝6.66×3.3+6.66×6.7＝6.66×（3.3+6.7）＝6.66×10＝66.64.8×7.8+78×0.52＝4.8×7.8+7.8×5.2＝7.8×（4.8+5.2）＝7.8×10＝78101×0.87-0.91×87＝1.01×87-0.91×87＝87×（1.01-0.91）＝87×0.1＝8.73.14×0.68+31.4×0.032＝3.14×0.68+3.14×0.32＝3.14×（0.68+0.32）＝3.14×1＝3142.3×16+2.3×23+2.3＝2.3×16+2.3×23+2.3×1＝2.3×（16+23+1）＝2.3×40＝92314×0