分析:(1)把1.6分解成0.8×2,再運(yùn)用乘法結(jié)合律簡(jiǎn)算;
(2)把48.7×0.266變成4.87×2.66,再運(yùn)用乘法分配律簡(jiǎn)算;
(3)把9.9分解成10-0.1,再運(yùn)用乘法分配律簡(jiǎn)算;
(4)運(yùn)用乘法交換律簡(jiǎn)算;
(5)把3.2分解成4×0.8再運(yùn)用乘法結(jié)合律簡(jiǎn)算;
(6)運(yùn)用乘法分配律簡(jiǎn)算.
解答:解:(1)1.6×3.9×1.25,
=0.8×2×3.9×1.25,
=(0.8×1.25)×(2×3.9),
=1×7.8,
=7.8;
(2)4.87×2.34+48.7×0.266,
=4.87×2.34+4.87×2.66,
=4.87×(2.34+2.66),
=4.87×5,
=24.35;
(3)0.49×9.9,
=0.49×(10-0.1),
=0.49×10-0.49×0.1,
=4.9-0.049,
=4.851;
(4)0.125×9.3×80,
=0.125×80×9.3,
=10×9.3,
=93;
(5)2.5×3.2×12.5,
=2.5×4×0.8×12.5,
=(2.5×4)×(0.8×12.5),
=10×10,
=100;
(6)4.4×3.6-3.4×3.6,
=(4.4-3.4)×3.6,
=1×3.6,
=3.6.
點(diǎn)評(píng):此題是考查四則混合運(yùn)算,要仔細(xì)觀察算式的特點(diǎn),靈活運(yùn)用一些定律進(jìn)行簡(jiǎn)便計(jì)算.