脱式计算.(能简算的要简算)
①×+÷3????????????????????? ②÷+×?????????? ?③[-(-)]÷④÷[(-)×]⑤×+×25%????????? ?⑥[45×(+)]÷5%⑦÷(2-)×????????????????? ⑧(-)×(÷)????? ⑨+(-)÷.
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①×+÷3,
=+×,
=×(),
=×1,
=;
②+×,
=×+,
=×(),
=×1,
=;
③[-(-)]÷,
=[-(-)]×4,
=×4,
=,
=2;
④÷[()×],
=÷[(-)×],
=÷[]
=6,
=3;
⑤×+×25%,
=×,
=(),
=;
⑥[45×()]÷5%,
=[45×+45×]×20,
=[10+15]×20,
=500;
⑦÷(2-)×,
=÷()×,
=×,
=;
⑧(-)×(÷),
=()×(),
=,
=;
⑨+(),
=+()×2,
=+×2,
=+,
=+,
=.
解析分析:第①②⑤⑥应用乘法分配律简便计算,使计算更加简便,第③④⑦⑧⑨题按分数、整数四则混合运算顺序计算.
点评:此题主要考查分数、整数、小数的四则混合运算的运算顺序和应用运算定律进行简便计算.