计算下面各题,怎样简便就怎样算 ×(+18)4÷-÷4×+××+÷719-19×-×.
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解:(1)×(+18),
=×+×18,
=1+10,
=11;
(2)4÷-÷4,
=5-,
=4;
(3)×+×,
=×(+),
=×1,
=;
(4)×+÷7,
=×+×,
=×(+),
=×1,
=;
(5)19-19×,
=19×(1-),
=19×,
=;
(6)-×,
=-,
=.
解析分析:(1)(3)(5)运用乘法分配律简算;
(2)同时运算除法,再算减法;
(4)先把除法变成乘法,再运用乘法分配律简算;
(6)先算乘法,再算减法.
点评:本题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.