题目内容
用简便方法计算.
125×27×8
35×102
5300÷4÷25
65.29-3.81-6.19
34×58+66×58.
解:(1)125×27×8,
=(125×8)×27,
=1000×27,
=27000;
(2)35×102,
=35×(100+2),
=3500+70,
=3570;
(3)5300÷4÷25,
=5300÷(4×25),
=5300÷100,
=53;
(4)65.29-3.81-6.19,
=65.29-(3.81+6.19),
=65.29-10,
=55.29;
(5)34×58+66×58,
=(34+66)×58,
=100×58,
=5800.
分析:(1)运用乘法交换律和结合律简算;
(2)把102看作100+2,运用乘法分配律简算;
(3)运用除法的性质简算;
(4)运用减法的性质简算;
(5)运用乘法分配律的逆运算简算.
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.
=(125×8)×27,
=1000×27,
=27000;
(2)35×102,
=35×(100+2),
=3500+70,
=3570;
(3)5300÷4÷25,
=5300÷(4×25),
=5300÷100,
=53;
(4)65.29-3.81-6.19,
=65.29-(3.81+6.19),
=65.29-10,
=55.29;
(5)34×58+66×58,
=(34+66)×58,
=100×58,
=5800.
分析:(1)运用乘法交换律和结合律简算;
(2)把102看作100+2,运用乘法分配律简算;
(3)运用除法的性质简算;
(4)运用减法的性质简算;
(5)运用乘法分配律的逆运算简算.
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.
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