用递等式计算下面各题:
(1)6.75×+37.5%×+37.5%??
(2)12.74-+2.26-9.875
(3)++++??????????
(4)4-[3.75×(1.2-)+].
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解:(1)6.75×+37.5%×+37.5%,
=6.75×37.5%+37.5%×+37.5%,
=(6.75++1)×37.5%,
=8×37.5%
=3;
(2)12.74-+2.26-9.875,
=(12.74+2.26)-(+9.875),
=15-10,
=5,
(3)++++,
=+9++99++999++9999+,
=(++++)+(9+99+999+9999),
=4+11106,
=11110;
(4)4-[3.75×(1.2-)+],
=4-[3.75×+],
=4-[3.25+]
=4-4,
=0;
解析分析:(1)把化成百分数37.5%,用乘法分配律进行简算,(2)把化成小数0.125,根据小数加减法的运算规律简算,(3)把带分数化成整数加分数的形式进行简算,(4)先算小括号里的减法,再算中括号里的乘法,再算中括号里的加法,最后算括号外的减法,
点评:考查了分数、小数、百分数的四则混合运算,灵活运用运算定律进行简算.