题目内容
下列各题怎么简算就怎么算.
(1)99.14×16+0.86×1
(2)125×0.59×0.8
(3)
(4)4725-379-221
(5)
.
解:(1)99.14×16+0.86×1,
=(100-0.86)×16+0.86×1,
=1600-0.86×16+0.86×1,
=1600-0.86×(16-1),
=1600-0.86×15,
=1600-12.9,
=1587.1;
(2)125×0.59×0.8,
=(125×0.8)×0.59,
=100×0.59,
=59;
(3)
,
=
×
×(0.25×4),
=
×1,
=
;
(4)4725-379-221,
=4725-(379+221),
=4725-600,
=4125;
(5)
,
=
×
+
×
,
=(
+
)×
,
=10×
,
=
.
分析:(1)根据数字特点,把99.14看作100-0.86,运用乘法分配律简算;
(2)(3)运用乘法交换律和结合律检算;
(4)运用减法的性质简算;
(5)先算括号内的,然后运用乘法分配律简算.
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.
=(100-0.86)×16+0.86×1,
=1600-0.86×16+0.86×1,
=1600-0.86×(16-1),
=1600-0.86×15,
=1600-12.9,
=1587.1;
(2)125×0.59×0.8,
=(125×0.8)×0.59,
=100×0.59,
=59;
(3)

=
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
=
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=
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(4)4725-379-221,
=4725-(379+221),
=4725-600,
=4125;
(5)

=
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
=(

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
=10×

=

分析:(1)根据数字特点,把99.14看作100-0.86,运用乘法分配律简算;
(2)(3)运用乘法交换律和结合律检算;
(4)运用减法的性质简算;
(5)先算括号内的,然后运用乘法分配律简算.
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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