计算下面各题,能简算的要简算.
12×(+-)÷×4×0.8×0.25×12.52.94×+4.06÷÷﹙×÷﹚(12-12×)÷.
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解:
(1)12×(+-),
=12×+12×-12×,
=6+4-3,
=10-3,
=7;
(2)÷×,
=×÷,
=1÷,
=;
(3)4×0.8×0.25×12.5,
=(4×0.25)×(0.8×12.5),
=1×10,
=10;
(4)2.94×+4.06÷,
=2.94×+4.06×,
=(2.94+4.06)×,
=7×,
=3;
(5)÷﹙×÷﹚,
=÷﹙÷﹚,
=÷,
=;
(6)(12-12×)÷,
=12×(1-)÷,
=12×÷,
=4÷,
=.
解析分析:(1)根据乘法分配律进行计算;
(2)根据乘法交换律进行计算;
(3)根据乘法交换律和结合律进行计算;
(4)根据乘法分配律进行计算;
(5)先算乘法,再算小括号里面的除法,最后算括号外面的除法;
(6)根据乘法分配律进行计算.
点评:此题主要考查分数、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.