计算下面各题,能简便的要简便. (×)×1-(+)××72.8+72.8×24×(+-)(+(-))×1.25×38+125%×3-12.5÷10.
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解:(1)(×)×,
=,
=;
(2)1-(+)×,
=1-,
=1-,
=;
(3)×72.8+72.8×,
=()×72.8,
=1×72.8,
=72.8;
(4)24×(+-),
=24×+24×-24×,
=6+4-8,
=2;
(5)(+(-))×,
=[()]×,
=[1-]×,
=,
=;
(6)1.25×38+125%×3-12.5÷10,
=(38+3-1)×1.25,
=40×1.25,
=50.
解析分析:(1)(2)依据四则运算计算顺序:先算第二级运算,再算第一级运算,如果只含有同一级运算,按照从左到右顺序计算,有括号先算括号里面的解答,(3)(4)(6)运用乘法分配律解答,(5)运用加法结合律解答.
点评:(1)正确依据四则运算计算顺序,(2)正确运用乘法分配律,进行四则运算是本题考查知识点.