脱式计算,能简便计算的要简算. (1)13÷0.4÷2.5(2)64×4.5+36×4.5(3)1.25×2.5×0.8(4)1.5×101-1.5(5)14.64+3.7×2.8(6)2.8×7.3+0.27×28.
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解:(1)13÷0.4÷2.5,
=13÷(0.4×2.5),
=13÷1,
=13;
(2)64×4.5+36×4.5,
=(64+36)×4.5,
=100×4.5,
=450;
(3)1.25×2.5×0.8,
=1.25×0.8×2.5,
=1×2.5,
=2.5;
(4)1.5×101-1.5,
=1.5×(101-1),
=1.5×100,
=150;
(5)14.64+3.7×2.8,
=14.64+10.36,
=25;
(6)2.8×7.3+0.27×28,
=2.8×7.3+2.7×2.8,
=2.8×(7.3+2.7),
=2.8×10,
=28.
解析分析:(1)根据除法的性质简算;
(2)(4)运用乘法分配律简算;
(3)运用乘法交换律简算;
(5)先算乘法,再算加法;
(6)先根据积不变规律把0.27×28变成2.7×2.8,再运用乘法分配律简算.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.