解:(1)25.3×12-33.46÷0.35,
=303.6-95.6,
=208;
(2)(
+
)÷
,
=(
+
)÷
,
=
×24,
=29;
(3)2.5×13×0.4,
=(2.5×0.4)×13,
=1×13,
=13;
(4)
÷[(
+
)×
],
=
÷[(
+
)×
],
=
÷[
×
],
=
,
=
,
=
;
(5)9.34-(2.34+0.49),
=(9.34-2.34)-0.49,
=7-0.49,
=6.51;
(6)
+
×19,
=(1+19)×
,
=20×
,
=16.
分析:(1)按運(yùn)算順序進(jìn)行計(jì)算,先算乘除,再算減法;
(2)按運(yùn)算順序進(jìn)行計(jì)算,先算括號(hào)內(nèi)的,再算括號(hào)外的,注意通分和約分;
(3)運(yùn)用乘法交換律和結(jié)合律簡(jiǎn)算;
(4)按運(yùn)算順序進(jìn)行計(jì)算,先算小括號(hào)內(nèi)的,再算中括號(hào)內(nèi)的,最后算括號(hào)外的;
(5)先運(yùn)用減法的性質(zhì)去括號(hào),再運(yùn)用加法結(jié)合律簡(jiǎn)算;
(6)把
看作
×1,運(yùn)用乘法分配律的逆運(yùn)算簡(jiǎn)算.
點(diǎn)評(píng):此題綜合考查四則混合運(yùn)算的法則和順序,同時(shí)考查了學(xué)生運(yùn)用運(yùn)算性質(zhì)、定律進(jìn)行簡(jiǎn)算的能力.