Question

19．计算下面各题，能简算的要简算．
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运用乘法分配律简便计算，
②先算小括号的加法再算减法，最后算乘法，
③先算小括号的减法，再根据除法的性质简算，
④把0.26+0.26+0.26+0.26变成0.26×4，再运用乘法结合律简算，
⑤先把6.73×5.8变成67.3×0.58，再用乘法分配律简算．

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

点评 此题考查小数四则混合运算顺序和灵活运用运算定律，分析数据找到正确的计算方法．