题目内容
简便计算 (1)35×(- ![]() | (2)12×(0.25-![]() |
(3)28x0.36+280×0.064 | (4)13×0.25+5÷4. |
解:(1)35×(1-
),
=35×1-35×
,
=35-(34+1)×
,
=35-3-
,
=32-
,
=31
;
(2)12×(0.25-
),
=12×(
-
),
=12×
-12×
,
=3-2,
=1;
(3)28×0.36+280×0.064,
=280×0.036+280×0.064,
=280×(0.036+0.064),
=280×0.1,
=28;
(4)13×0.25+5÷4,
=13×
+5×
,
=(13+5)×
,
=18×
,
=4.5.
分析:(1)运用乘法分配律简算;
(2)把0.25化为分数,运用乘法分配律简算;
(3)把原式变为280×0.036+280×0.064,运用乘法分配律简算;
(4)把0.25化为分数,把除法转化为乘法,运用乘法分配律简算.
点评:完成此题,注意分析式中数据,灵活运用运算定律,进行简便计算.

=35×1-35×

=35-(34+1)×

=35-3-

=32-

=31

(2)12×(0.25-

=12×(


=12×


=3-2,
=1;
(3)28×0.36+280×0.064,
=280×0.036+280×0.064,
=280×(0.036+0.064),
=280×0.1,
=28;
(4)13×0.25+5÷4,
=13×


=(13+5)×

=18×

=4.5.
分析:(1)运用乘法分配律简算;
(2)把0.25化为分数,运用乘法分配律简算;
(3)把原式变为280×0.036+280×0.064,运用乘法分配律简算;
(4)把0.25化为分数,把除法转化为乘法,运用乘法分配律简算.
点评:完成此题,注意分析式中数据,灵活运用运算定律,进行简便计算.

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