分析:①按運(yùn)算順序從左往右依次運(yùn)算;
②③運(yùn)用加法交換律與結(jié)合律簡(jiǎn)算;
④運(yùn)用加法的性質(zhì)簡(jiǎn)算;
⑤⑥運(yùn)用加法交換律與結(jié)合律簡(jiǎn)算.
解答:解:①6.21-3.8+2.2,
=2.41+2.2,
=4.61;
②6.03+3.7+2.97,
=(6.03+2.97)+3.7,
=9+3.7,
=12.7;
③17.43-6.57-2.43,
=17.43-(6.57+2.43),
=17.43-9,
=8.43;
④20.47-(1.47+6.8),
=20.47-1.47-6.8,
=19-6.8,
=12.2;
⑤13.26+4.71+3.47+5.29,
=(13.26+3.47)+(4.71+5.29),
=16.73+10,
=26.73;
⑥22.74+8.68-13.74,
=(22.74-13.74)+8.68,
=9+8.68,
=17.68.
點(diǎn)評(píng):此題考查了小數(shù)的四則混合運(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)算定律或性質(zhì)進(jìn)行簡(jiǎn)便計(jì)算.