2506-10517÷13+14×106
[0.8+0.75×(0.65-0.25)]÷0.01
455×7.6+112÷+43.3×76
+++…+
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解:(1)2506-10517÷13+14×106,
=2506-809+1484,
=1697+1484,
=3181;
(2)[0.8+0.75×(0.65-0.25)]÷0.01,
=[0.8+0.75×0.4]÷0.01,
=[0.8+0.3]÷0.01,
=1.1÷0.01,
=110;
(3)455×7.6+112÷+43.3×76,
=455×7.6+112×7.6+433×7.6,
=(455+112+433)×7.6,
=1000×7.6,
=7600;
(4)+++…+,
=1+2×(-+-++…+-),
=1+2×(),
=1+,
=.
解析分析:(1)、(2)按照先算乘除,再算加减,有括号的先算括号里面的运算顺序计算;
(3)用乘法分配律简算;
(4)因为:(1+2+…+n)=n(n+1)÷2,那么:==2(-),由此求解.
点评:第(4)题较复杂,先找出规律,再根据规律化简求解.