用简便方法计算.
①5%×9.9;??????????????????
②4.62+9.9;?????????????????
③4×0.6+0.6÷.
网友回答
解:①5%×9.9;,
=5%×(10-0.1),
=5%×10-5%×0.1,
=0.5-0.005,
=0.495;
②4.62+9.9,
=(4+0.62)+(10-0.1),
=(4+10)+(0.62-0.1),
=14+0.52,
=14.52;
③4×0.6+0.6÷,
=×0.6+0.6×,
=×(0.6+0.6),
=×1.2,
=×,
=.
解析分析:①把9.9变成(10-0.10,再用乘法分配律简算;②把9.9变成(10-0.1),再运用加法结合律简算;③运用乘法分配律简算.
点评:像①②这种类型的题目是运用凑整法把数字变成较易算的数字再运用运算定律简算,这是常用的简算方法,要熟练运用.