Question

6．用脫式計(jì)算．
①8.5×14.3+5.7×8.5                 
②41.7-0.5×0.7-1.65
③21.36÷0.8-12.9                     
④0.75×18÷0.15．

Answer 1

分析 ①根據(jù)乘法分配律簡(jiǎn)算；
②先算乘法，再根據(jù)減法的性質(zhì)簡(jiǎn)算；
③先算除法，再算減法；
④根據(jù)乘法交換律簡(jiǎn)算．

解答 解：①8.5×14.3+5.7×8.5                 
=8.5×（14.3+5.7）
=8.5×20
=170

②41.7-0.5×0.7-1.65
=41.7-0.35-1.65
=41.7-（0.35+1.65）
=41.7-2
=39.7

③21.36÷0.8-12.9      
=26.7-12.9
=13.8
               
④0.75×18÷0.15
=0.75÷0.15×18
=5×18
=90

點(diǎn)評(píng) 本題考查了四則混合運(yùn)算，注意運(yùn)算順序和運(yùn)算法則，靈活運(yùn)用所學(xué)的運(yùn)算定律進(jìn)行簡(jiǎn)便計(jì)算．