怎样简便就怎样算. 4.27÷0.7×1.318.9-18.9÷1.40.25×4080.25×1.25×160.4×99+0.412.5×1.7+8.3×12.5.
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解:
(1)4.27÷0.7×1.3,
=6.1×1.3,
=7.93;
(2)18.9-18.9÷1.4,
=18.9-13.5,
=5.4;
(3)0.25×408,
=0.25×(4×102),
=(0.25×4)×102,
=1×102,
=102;
(4)0.25×1.25×16,
=0.25×1.25×(2×8),
=(0.25×2)×(1.25×8),
=0.5×10,
=5;
(5)0.4×99+0.4,
=0.4×(99+1),
=0.4×100,
=40;
(6)12.5×1.7+8.3×12.5,
=12.5×(1.7+8.3),
=12.5×10,
=125.
解析分析:(1)先算除法,再算乘法;(2)先算除法,再算减法;(3)根据乘法结合律进行计算;(4)根据乘法交换律和结合律进行计算;(5)根据乘法分配律进行简算;(6)根据乘法分配律进行简算.
点评:四则混合运算,先弄清运算顺序,然后再进一步计算,能简算的要简算.