分析:(1)先算小括號(hào)里面的除法,再算小括號(hào)里面的減法,最后算括號(hào)外的乘法;
(2)先算小括號(hào)里面的減法,再把24分解成8×3,運(yùn)用乘法結(jié)合律簡(jiǎn)算,最后算除法;
(3)先把44分解成4×11,再運(yùn)用乘法結(jié)合律簡(jiǎn)算;
(4)運(yùn)用乘法交換律簡(jiǎn)算;
(5)先把9.9分解成10-0.1,再運(yùn)用乘法分配律簡(jiǎn)算;
(6)運(yùn)用乘法分配律簡(jiǎn)算.
解答:解:(1)0.85×(21.9-7.6÷4),
=0.85×(21.9-1.9),
=0.85×20,
=17;
(2)(15-13.75)×24÷2.5,
=1.25×24÷2.5,
=1.25×8×3÷2.5,
=10×3÷2.5,
=30÷2.5,
=12;
(3)2.5×44,
=2.5×4×11,
=10×11,
=110;
(4)12.5×17.8×0.8,
=12.5×0.8×17.8,
=10×17.8,
=178;
(5)9.9×5.4,
=(10-0.1)×5.4,
=10×5.4-0.1×5.4,
=54-0.54,
=53.46;
(6)9.4×5.8+10.6×5.8,
=(9.4+10.6)×5.8,
=20×5.8,
=116.
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.