Question

用簡便方法計(jì)算下面各題．

①2.8×25	②0.13×102	③0.3×2.5×0.4
④2.33×0.5×0.4×5	⑤0.8×630×0.125	⑥3.12×4+1.88×4．

Answer 1

分析：①可將2.8變?yōu)?×0.4后根據(jù)乘法分配律計(jì)算．
②可將102拆分為100+2后，根據(jù)乘法分配律計(jì)算．
③⑥可根據(jù)乘法分配律計(jì)算．
④可根據(jù)乘法結(jié)合律計(jì)算．
⑤可根據(jù)乘法交換律與結(jié)合律計(jì)算．

解答：解：①2.8×25
=7×（0.4×25）
=7×10
=70

②0.13×102
=0.13×（100+2）
=0.13×100+0.13×2
=13+0.26
=13.26

③0.3×2.5×0.4
=0.3×（2.5×0.4）
=0.3×1
=0.3

④2.33×0.5×0.4×5
=2.33×（0.5×0.4×0.5）
=2.33×0.1
=0.233

⑤0.8×630×0.125
=（0.8×0.125）×630
=0.1×630
=63

⑥3.12×4+1.88×4
=（3.12+1.88）×4
=5×4
=20

點(diǎn)評(píng)：完成此類題目要注意分析式中數(shù)據(jù)的特點(diǎn)，然后運(yùn)用合適的方法計(jì)算．