Question

19．計算下面各題，能簡算的要簡算．
16.8×10.1            
33×[65.9-（1.2+4.7）]
（45.9-32.7）÷8÷0.125
（0.26+0.26+0.26+0.26）×2.5                    
6.73×5.8+0.42×67.3．

Answer 1

分析 ①運用乘法分配律簡便計算，
②先算小括號的加法再算減法，最后算乘法，
③先算小括號的減法，再根據(jù)除法的性質(zhì)簡算，
④把0.26+0.26+0.26+0.26變成0.26×4，再運用乘法結(jié)合律簡算，
⑤先把6.73×5.8變成67.3×0.58，再用乘法分配律簡算．

解答 解：①16.8×10.1  
=16.8×（10+0.1）
=16.8×10+16.8×0.1
=168+1.68
=169.68          

②33×[65.9-（1.2+4.7）]
=33×[65.9-5.9]
=33×60
=1980

③（45.9-32.7）÷8÷0.125
=13.2÷（8×0.125）
=13.2÷1
=13.2

④（0.26+0.26+0.26+0.26）×2.5
=（0.26×4）×2.5
=0.26×4×2.5
=0.26×（4×2.5）
=0.26×10
=2.6                   

⑤6.73×5.8+0.42×67.3
=67.3×0.58+0.42×67.3
=67.3×（0.58+0.42）
=67.3×1
=67.3

點評 此題考查小數(shù)四則混合運算順序和靈活運用運算定律，分析數(shù)據(jù)找到正確的計算方法．