能简算的要简算:
(1)241×690÷339÷345×678÷241
(2)6-0.65+5×99
(3)356×84-4×356-80÷
(4)[3.75-(0.2+)×4]÷13.5%
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解:(1)241×690÷339÷345×678÷241,
=241×690×××678×,
=(241×)×(×678)×(690×),
=1×2×2,
=4;
(2)6-0.65+5×99,
=5.35+5.35×99,
=(1+99)×5.35,
=100×5.35,
=535;
(3)356×84-4×356-80÷,
=356×84-4×356-80×356,
=356×(84-4-80),
=356×0,
=0;
(4)[3.75-(0.2+)×4]÷13.5%,
=[3-()×4]÷13.5%,
=[3-×]÷13.5%,
=[-]÷13.5%,
=÷13.5%,
=1.35÷0.135,
=10.
解析分析:(1)241×690÷339÷345×678÷241,此题把除法改为乘法,通过乘法交换律和结合律简算;(2)6-0.65+5×99,把分数化为小数为5.35,因为6-0.65=5.35,然后用乘法分配律的逆运算简算;(3)356×84-4×356-80÷,把除法改为乘法后,应用乘法分配律的逆运算简算;(4)[3.75-(0.2+)×4]÷13.5%,按运算顺序计算,先算小括号内的,再算中括号里的,最后算括号外的,在运算中注意数的转化.
点评:此题考查了学生抓住特点、巧妙解答的能力,以及对运算顺序的掌握情况.