解:(1)1.25×32×2.5,
=(1.25×8)×(4×2.5),
=10×10,
=100;
(2)8.57×1.4+85.7×0.86,
=85.7×(0.14+0.86),
=85.7×1,
=85.7;
(3)
,
=
(
),
=
1,
=
.
分析:(1)1.25×32×2.5,轉(zhuǎn)化為1.25×8×4×2.5,再運(yùn)用乘法結(jié)合律進(jìn)行簡(jiǎn)算;
(2)8.57×1.4+85.7×0.86,首先根據(jù)積的變化的規(guī)律,一個(gè)因數(shù)擴(kuò)大10,另一個(gè)因數(shù)縮小10倍積不變;將原式轉(zhuǎn)化為85.7×0.14+85.7×0.86,再運(yùn)用乘法分配律進(jìn)行簡(jiǎn)算;
(3)
,把除數(shù)
轉(zhuǎn)化為乘它的倒數(shù)
,再運(yùn)用乘法分配律進(jìn)行簡(jiǎn)算.
點(diǎn)評(píng):此題考查的目的是運(yùn)用乘法的結(jié)合律、乘法分配律對(duì)小數(shù)、分?jǐn)?shù)四則混合運(yùn)算進(jìn)行簡(jiǎn)便計(jì)算.