题目内容
计算下面各题,能简算的要简算.
| ( | ||
| 2012× | 4×5×( |
解:(1)
×
×
,
=
×(
×
),
=
×1,
=
;
(2)(
+
)×24,
=
×24+
×24,
=20+9,
=29;
(3)
×101-
,
=
×(101-1),
=
×100,
=30;
(4)2012×
,
=(2011+1)×
,
=2011×
+1×
,
=2010+
,
=2010
;
(5)
×0.2+0.8×
,
=
×(0.2+0.8),
=
×1,
=
;
(6)4×5×(
-
),
=(4×
×5)-(5×
×4),
=3×5-2×4,
=15-8,
=7.
分析:(1)运用乘法结合律简算;
(2)(3)(5)(6)运用乘法分配律简算;
(4)先把2012分解成(2011+1)再运用乘法分配律简算.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
=
=
=
(2)(
=
=20+9,
=29;
(3)
=
=
=30;
(4)2012×
=(2011+1)×
=2011×
=2010+
=2010
(5)
=
=
=
(6)4×5×(
=(4×
=3×5-2×4,
=15-8,
=7.
分析:(1)运用乘法结合律简算;
(2)(3)(5)(6)运用乘法分配律简算;
(4)先把2012分解成(2011+1)再运用乘法分配律简算.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
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