脱式计算,能简算的要简算. 1.69÷1.3+2.5×0.4 1.25×32×2.596.5×105-5×96.518.75-0.43-4.57.
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解:
(1)1.69÷1.3+2.5×0.4,
=1.3+1,
=2.3;
(2)1.25×32×2.5,
=1.25×(8×4)×2.5,
=(1.25×8)×(4×2.5),
=10×10,
=100;
(3)96.5×105-5×96.5,
=96.5×(105-5),
=96.5×100,
=9650;
(4)18.75-0.43-4.57,
=18.75-(0.43+4.57),
=18.75-5,
=13.75.
解析分析:(1)先算除法和乘法,再算加法;(2)根据乘法交换律和结合律进行计算;(3)根据乘法分配律进行计算;(4)根据连减的性质进行计算.
点评:四则运算,先弄清运算顺序,然后再进一步计算,能简算的要简算.