Question

【题目】用简便方法计算
3.9×10.1
2.64÷5÷0.2
2.5×0.125×3.2×1.9

Answer 1

【答案】解：①3.9×10.1
=3.9×（10+0.1）
=3.9×10+3.9×0.1
=39+0.39
=39.39
②2.64÷5÷0.2
=2.64÷（5×0.2）
=2.64÷1
=2.64
③2.5×0.125×3.2×1.9
=2.5×0.125×（0.4×8）×1.9
=（2.5×0.4）×（0.125×8）×1.9
=1×1×1.9
=1.9
【解析】（1）利用乘法分配律计算；（2）利用除法性质计算；（3）利用乘法交换律与结合律计算．