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计算下面各题.(1)495÷+495÷45 (2)3.3×+0.75×5+75% (3)3.68-0.82-0.18(4)56× (5)1.25×32×0.25 (6)12×[+()].

编辑:chaxungu时间:2026-04-26 09:49:15分类:小学数学题库

计算下面各题.
(1)495÷数学公式+495÷45  
(2)3.3×数学公式+0.75×5数学公式+75%     
(3)3.68-0.82-0.18
(4)56×数学公式         
(5)1.25×32×0.25        
(6)12×[数学公式+(数学公式)].解:(1)495÷+495÷45,
=495×+495×
=495×(),
=495×1,
=495;
(2)3.3×+0.75×5+75%,
=3.3×0.75+0.75×5.7+0.75,
=0.75×(3.3+5.7+1),
=0.75×10,
=7.5;
(3)3.68-0.82-0.18,
=3.68-(0.82+0.18),
=3.68-1,
=2.68;
(4)56×
=(57-1)×
=57×-
=56-
=55
(5)1.25×32×0.25,
=1.25×8×4×0.25,
=(1.25×8)×(4×0.25),
=10×1,
=10;
(6)12×[+()],
=12×[],
=12×[1-],
=12×
=10.
分析:(1)495÷+495÷45,先把除法改为乘法,然后用乘法分配律的逆运算简算;
(2)3.3×+0.75×5+75%,把、5和75%化为小数后,用乘法分配律的逆运算简算;
(3)3.68-0.82-0.18,用减法的性质简算;
(4)56×,把56看作(57-1),进行简算;
(5)1.25×32×0.25,把32看成8×4,然后用乘法结合律简算;
(6)12×[+()],先去小括号,结合结果为1,中括号的结果的出后,与12约分.
点评:此题重点考查学生的运算技巧,要想达到简算的目的,必须熟练掌握运算定律.