题目内容
(2012?广州一模)下列各题怎样简便就怎样计算
(1)
+(5+7
×3
)×
(2)1.75×0.24+0.76÷
(3)2012×20.11-201.2×201
(4)1-
-
-
-
.
(1)
1 |
5 |
4 |
5 |
1 |
3 |
3 |
31 |
(2)1.75×0.24+0.76÷
4 |
7 |
(3)2012×20.11-201.2×201
(4)1-
1 |
10 |
1 |
100 |
1 |
1000 |
1 |
10000 |
分析:(1)按则运算的顺序,先算小括号里的乘,再算小括号里的加,然后算括号外面的乘,最后算括号外面的加;
(2)把0.76÷
变成0.76×1.75,利用乘法的分配律变成1.75×(0.24+0.76)计算简便;
(3)把2012×20.11变成201.2×201.1,利用乘法的分配律变,201.2×(201.1-201)计算简便;
(4)把原算是变成1-(
+
+
+
)计算简便.
(2)把0.76÷
4 |
7 |
(3)把2012×20.11变成201.2×201.1,利用乘法的分配律变,201.2×(201.1-201)计算简便;
(4)把原算是变成1-(
1 |
10 |
1 |
100 |
1 |
1000 |
1 |
10000 |
解答:解:
+(5+7
×3
)×
,
=
+(5+26)×
,
=
+31×
,
=3
;
(2)1.75×0.24+0.76÷
,
=1.75×0.24+0.76×1.75,
=1.75×(0.24+0.76),
=1.75×1,
=1.75;
(3)2012×20.11-201.2×201,
=201.2×201.1-201.2×201,
=201.2×(201.1-201),
=201.2×0.1,
=20.12;
(4)1-
-
-
-
,
=1-(
+
+
+
),
=1-
,
=
1 |
5 |
4 |
5 |
1 |
3 |
3 |
31 |
=
1 |
5 |
3 |
31 |
=
1 |
5 |
3 |
31 |
=3
1 |
5 |
(2)1.75×0.24+0.76÷
4 |
7 |
=1.75×0.24+0.76×1.75,
=1.75×(0.24+0.76),
=1.75×1,
=1.75;
(3)2012×20.11-201.2×201,
=201.2×201.1-201.2×201,
=201.2×(201.1-201),
=201.2×0.1,
=20.12;
(4)1-
1 |
10 |
1 |
100 |
1 |
1000 |
1 |
10000 |
=1-(
1 |
10 |
1 |
100 |
1 |
1000 |
1 |
10000 |
=1-
1111 |
10000 |
=
8889 |
10000 |
点评:考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算律简便计算.
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