72-15.72+4.28????????????????????
4500÷125
25×125×32?????????????????????
125×34+67×125-125
3960÷[145-(27+18)]
35.33-(15.33-3.34)+6.66.
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解:①72-15.72+4.28
=56.28+4.28,
=60.56;
②4500÷125,
=4.5×1000÷125,
=4.5×(1000÷125),
=4.5×8,
=36;
③25×125×32,
=(25×4)×(125×8),
=100×1000,
=100000;
④125×34+67×125-125,
=125×(34+67-1),
=125×100,
=12500;
⑤3960÷[145-(27+18)],
=3960÷[145-45],
=3960÷100,
=39.6;
⑥35.33-(15.33-3.34)+6.66,
=(35.33--15.33)+(3.34+6.66),
=20+10,
=30.
解析分析:①⑤按照整数的四则混合运算进行计算,有括号的先算括号内部的.②可将式中4500拆分成4.5×1000,再用1000÷125=8,再用4.5×8.这样计算更加简便;③可将32拆分成4×8在运用乘法交换律,结合律行计算;④运用乘法的分配律进行计算;⑥运用一个数减去两个数的差,可以用这个数减去被减数加上减数.
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.