Question

8．用簡(jiǎn)便方法計(jì)算．
3.9+5.02+3.98+1.1               
87-2.123-0.877
8×62×125                    
101×92．

Answer 1

分析 ①根據(jù)加法交換律及結(jié)合律計(jì)算；
②根據(jù)減法性質(zhì)進(jìn)行計(jì)算；
③根據(jù)乘法交換律及結(jié)合律計(jì)算；
④把101寫成100+1，再根據(jù)乘法分配律進(jìn)行計(jì)算．

解答 解：①3.9+5.02+3.98+1.1  
=（3.9+1.1）+（5.02+3.98）
=5+9
=14
            
②87-2.123-0.877
=87-（2.123+0.877）
=87-3
=84

③8×62×125
=8×125×62
=1000×62
=62000
                    
④101×92
=（100+1）×92
=100×92+92
=9200+92
=9292

點(diǎn)評(píng) 完成本題要注意分析式中數(shù)據(jù)，運(yùn)用合適的簡(jiǎn)便方法計(jì)算．