脫式計(jì)算
4.8+4.2÷60              
279+141+121           25×23×4
102×88-2×88           (40+4)×25          13.75-5.28-4.72.
分析:(1)先算除法,再算加法;
(2)運(yùn)用加法交換律簡算;
(3)運(yùn)用乘法交換律簡算;
(4)(5)運(yùn)用乘法分配律簡算;
(6)運(yùn)用減法的性質(zhì)簡算.
解答:解:(1)4.8+4.2÷60,
=4.8+0.07,
=4.87;

(2)279+141+121,
=(279+121)+141,
=300+141,
=441;

(3)25×23×4,
=(25×4)×23,
=100×23,
=2300;

(4)102×88-2×88,
=(102-2)×88,
=100×88,
=8800;

(5)(40+4)×25,
=40×25+4×25,
=1000+100,
=1100;

(6)13.75-5.28-4.72,
=13.75-(5.28+4.72),
=13.75-10,
=3.75.
點(diǎn)評(píng):完成本題,要注意分析式中數(shù)據(jù),運(yùn)用合適的簡便方法計(jì)算.
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