28.4×13-325.62÷8.1  
312.56-13.49-(16.51-81.44)
9.7+3.6÷0.8×1.3-1.3  
45.8×7.36+45.8+1.64×45.8
10-(0.81+0.9×5.1)÷1.2
[9.7+(7.2-5.52)÷1.4]×0.6.

解:(1)28.4×13-325.62÷8.1,
=369.2-40.2,
=329;

(2)312.56-13.49-(16.51-81.44),
=312.56-13.49-16.51+81.44,
=(312.56+81.44)-(13.49+16.51),
=394-30,
=364;

(3)9.7+3.6÷0.8×1.3-1.3,
=9.7+4.5×1.3-1.3,
=9.7+5.85-1.3,
=14.25;

(4)45.8×7.36+45.8+1.64×45.8,
=45.8×(7.36+1+1.64),
=45.8×10,
=458;

(5)10-(0.81+0.9×5.1)÷1.2,
=10-(0.9×0.9+0.9×5.1)÷1.2
=10-0.9×(0.9+5.1)÷1.2,
=10-0.9×6÷1.2,
=10-0.9×(6÷1.2),
=10-0.9×5,
=10-4.5,
=5.5;

(6)[9.7+(7.2-5.52)÷1.4]×0.6,
=[9.7+1.68÷1.4]×0.6,
=[9.7+1.2]×0.6,
=10.9×0.6,
=6.54.
分析:(1)先算乘除,再算減法;
(2)去括號(hào),運(yùn)用加法交換律與結(jié)合律簡(jiǎn)算;
(3)先算除法和乘法,然后從左往右依次運(yùn)算;
(4)運(yùn)用乘法分配律簡(jiǎn)算;
(5)把0.81看作0.9×0.9,括號(hào)內(nèi)運(yùn)用乘法分配律簡(jiǎn)算;
(6)先算小括號(hào)內(nèi)的,再算中括號(hào)內(nèi)的除法,然后算中括號(hào)內(nèi)的加法,最后算括號(hào)外的.
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)算定律進(jìn)行簡(jiǎn)便計(jì)算.
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