解:(1)[25-(
-
)×12]÷5
,
=[25-
×12]÷5
,
=(25-3)÷5
=22
,
=4;
(2)
×
+
×
,
=
×
+
×
,
=(
+
)×
,
=1×
,
=
;
(3)99×101,
=99×(100+1),
=99×100+99×1,
=9900+99,
=9999;
(4)1.25×32×2.5,
=1.25×(4×8)×2.5,
=(1.25×8)×(2.5×4),
=10×10,
=100;
(5)4.3×6.7+0.67×67-6.7,
=4.3×6.7+6.7×6.7-6.7,
=(4.3+6.7-1)×6.7,
=10×6.7,
=67.
分析:(1)先算小括號(hào)里面的減法,再算中括號(hào)里面的乘法,然后算中括號(hào)里面的減法,最后算括號(hào)外的除法;
(2)先根據(jù)積不變規(guī)律把
×
變成
×
,再運(yùn)用乘法分配律簡算;
(3)先把101分解成100+1,再運(yùn)用乘法分配律簡算;
(4)先把32分解成4×8,再運(yùn)用乘法結(jié)合律簡算;
(5)先根據(jù)積不變規(guī)律0.67×67變成6.7×6.7,再運(yùn)用乘法分配律簡算.
點(diǎn)評: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)行簡便計(jì)算.