Question

16．用簡便方法計(jì)算：
9.62+24.4+13.38+5.6                  
28.63-6.3-4.63
1.25×2.5×0.8×4                   
 2.71×6.5+2.5×2.71+2.71．

Answer 1

分析 ①運(yùn)用加法交換律和結(jié)合律簡算，
②運(yùn)用加法交換律可簡算，
③運(yùn)用乘法交換律和結(jié)合律簡算，
④逆用乘法分配律可簡算．

解答 解：①9.62+24.4+13.38+5.6
=（9.62+13.38）+（24.4+5.6）
=23+30
=53                  

②28.63-6.3-4.63
=（28.63-4.63）-6.3
=24-6.3
=17.7

③1.25×2.5×0.8×4 
=（1.25×0.8）×（2.5×4）
=1×10
=10                  

④2.71×6.5+2.5×2.71+2.71
=2.71×（6.5+2.5+1）
=2.71×10
=27.1

點(diǎn)評 此題考查小數(shù)四則混合運(yùn)算順序和靈活運(yùn)用運(yùn)算定律，分析數(shù)據(jù)找到正確的計(jì)算方法．