解:①4.86×9.7+0.486×3,
=4.86×9.7+4.86×0.3,
=4.86×(9.7+0.3),
=4.86×10,
=48.6;
②(1.25+12.5+125)×8,
=1.25×8+12.5×8+125×8,
=10+100+1000,
=1110;
③0.01+3.75×0.8÷0.25
=0.01+12,
=12.01;
④97.73-(17.73+4.9)-5.1,
=97.73-17.73-4.9-5.1,
=80-(4.9+5.1),
=80-10,
=70;
⑤5.4÷(3.94+0.86)×0.8,
=5.4÷4.8×0.8,
=1.125×0.8,
=0.9;
⑥(8.1-5.4)÷3.6+8.5,
=2.7÷3.6+8.5,
=0.75+8.5,
=9.25.
分析:①4.86×9.7+0.486×3把算式變成4.86×9.7+4.86×0.3,再利用乘法的分配律變成4.86×(9.7+0.3)計(jì)算簡便;
②(1.25+12.5+125)×8利用乘法的分配律計(jì)算簡便;
③0.01+3.75×0.8÷0.25按運(yùn)算順序先做乘除,再算加;
④97.73-(17.73+4.9)-5.1先去掉括號(hào)變成97.73-17.73-(4.9
+5.1)計(jì)算簡便;
⑤5.4÷(3.94+0.86)×0.8先算括號(hào)里的加,再算括號(hào)外面的除乘;
⑥(8.1-5.4)÷3.6+8.5先算括號(hào)里的減,再算括號(hào)外面的除加.
點(diǎn)評(píng):考查了運(yùn)算定律與簡便運(yùn)算,四則混合運(yùn)算.注意運(yùn)算順序和運(yùn)算法則,靈活運(yùn)用所學(xué)的運(yùn)算律簡便計(jì)算.