用你喜歡的方法計(jì)算下列各題.
(1)3.6+(7.43-3.83)×2.5 (2)100×9.5×0.98+9.5×2
(3)54.3×1.8+54.3×0.3-54.3×0.1 (4)〔(2+2.8)÷0.6-1.5〕×0.04.
解:(1)3.6+(7.43-3.83)×2.5
=3.6+3.6×2.5,
=3.6+9,
=12.6;
(2)100×9.5×0.98+9.5×2
=9.5×98+9.5×2,
=9.5×(98+2),
=9.5×100,
=950;
(3)54.3×1.8+54.3×0.3-54.3×0.1
=54.3×(1.8+0.3-0.1),
=54.3×2,
=108.6;
(4)〔(2+2.8)÷0.6-1.5〕×0.04
=(4.8÷0.6-1.5)×0.04,
=(8-1.5)×0.04,
=6.5×0.04,
=0.26.
分析:通過觀察算式特點(diǎn)可知:(1)在計(jì)算過程中可利用乘法結(jié)合律,(2)和(3)利用乘法分配律計(jì)算,(4)按照運(yùn)算順序計(jì)算.
點(diǎn)評:在小數(shù)四則混合運(yùn)算中,可以先觀察算式數(shù)字的特點(diǎn),能簡算的要簡算,不能簡算的就按運(yùn)算順序計(jì)算.