解:①0.65×101,
=0.65×(100+1),
=0.65×100+0.65,
=65+0.65,
=65.65;
②76.43-5.33-4.67,
=76.43-(5.33+4.67),
=76.43-10,
=66.43;
③3.4÷[7.8-(3.9+2.2)],
=3.4÷[7.8-6.1],
=3.4÷1.7,
=2;
④13.7÷12.5÷0.8,
=13.7÷(12.5×0.8),
=13.7÷10,
=1.37;
⑤3.25×8.4+6.75×8.4,
=(3.25+6.75)×8.4,
=10×8.4,
=84;
⑥[1.4×2-(0.65+0.55)]÷40,
=[2.8-1.2]÷40,
=1.6÷40,
=0.04.
分析:①0.65×101,應(yīng)把101拆成(100+1);
②76.43-5.33-4.67,應(yīng)用減法的性質(zhì)把此式變?yōu)?6.43-(5.33+4.67);
③3.4÷[7.8-(3.9+2.2)],不能簡(jiǎn)算,按運(yùn)算順序進(jìn)行;
④13.7÷12.5÷0.8,應(yīng)用除法的性質(zhì),把原式變?yōu)?br />13.7÷(12.5×0.8);
⑤3.25×8.4+6.75×8.4,應(yīng)用乘法分配律的逆運(yùn)算進(jìn)行簡(jiǎn)算;
⑥[1.4×2-(0.65+0.55)]÷40,按運(yùn)算順序進(jìn)行計(jì)算.
點(diǎn)評(píng):此題重點(diǎn)考查學(xué)生的運(yùn)算定律及其運(yùn)算順序,特別注意減法和除法性質(zhì)的運(yùn)用,即a-b-c=a-(b+c);a÷b÷c=a÷(b×c).