用简便方法计算.(要写出简算的过程)?
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解题思路:(1)运用乘法结合律简算;
(2)先去括号,再运用加法交换律简算;
(3)先把除法化为乘法,再逆用乘法分配律简算;
(4)先去括号,再运用乘法交换律和结合律简算.
(1)2.5×0.125×32
=2.5×([1/8]×32)
=2.5×4
=10
(2)38.32-(4.7-2.68)
=38.32-4.7+2.68
=38.32+2.68-4.7
=41-4.7
=36.3
(3)4.8×[1/5]+4.2÷5+[1/5]
=4.8×[1/5]+4.2×[1/5]+[1/5]
=[1/5]×(4.8+4.2+1)
=[1/5]×10
=2
(4)[2/27]×(15×[27/28])×[2/15]
=[2/27]×15×[27/28]×[2/15]
=([2/27]×[27/28])×(15×[2/15])
=[1/14]×2
=[1/7]
,9,用简便方法计算.(要写出简算的过程)
(1)2.5×0.125×32
(2)38.32-(4.7-2.68)
(3)4.8×[1/5]+4.2÷5+[1/5]
(4)[2/27]×(15×[27/28])×[2/15].
(2)先去括号,再运用加法交换律简算;
(3)先把除法化为乘法,再逆用乘法分配律简算;
(4)先去括号,再运用乘法交换律和结合律简算.
(1)2.5×0.125×32
=2.5×([1/8]×32)
=2.5×4
=10
(2)38.32-(4.7-2.68)
=38.32-4.7+2.68
=38.32+2.68-4.7
=41-4.7
=36.3
(3)4.8×[1/5]+4.2÷5+[1/5]
=4.8×[1/5]+4.2×[1/5]+[1/5]
=[1/5]×(4.8+4.2+1)
=[1/5]×10
=2
(4)[2/27]×(15×[27/28])×[2/15]
=[2/27]×15×[27/28]×[2/15]
=([2/27]×[27/28])×(15×[2/15])
=[1/14]×2
=[1/7]
,9,用简便方法计算.(要写出简算的过程)
(1)2.5×0.125×32
(2)38.32-(4.7-2.68)
(3)4.8×[1/5]+4.2÷5+[1/5]
(4)[2/27]×(15×[27/28])×[2/15].
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