题目内容
(2013?广州模拟)计算下面各题能简便的尽量简便
(1)
|
(2)9
| ||||||||||||||||||
(3)18÷[
|
(4)
|
分析:(1)先算小括号里面的减法,再算中括号里面的减法,最后算乘法;
(2)根据加法交换律和结合律进行计算;
(3)先算减法,再算加法,最后算除法;
(4)根据乘法分配律进行计算.
(2)根据加法交换律和结合律进行计算;
(3)先算减法,再算加法,最后算除法;
(4)根据乘法分配律进行计算.
解答:解:
(1)
×[
-(
-
)],
=
×[
-
],
=
×
,
=
;
(2)9
+99
+999
+9999
-
,
=(9+
)+(99+
)+(999+
)+(9999+
)-
,
=(9+99+999+9999)+(
+
+
+
-
),
=9+99+999+9999,
=(10-1)+(100-1)+(1000-1)+(10000-1),
=(10+100+1000+10000)-(1+1+1+1),
=11110-4,
=11106;
(3)18÷[
+(
-
)],
=18÷[
+
],
=18÷
,
=16;
(4)
×2003+2005×25%+2004×0.75,
=0.25×2003+2005×0.25+2004×(0.25×3),
=0.25×(2003+2005+2004×3),
=0.25×2004×5,
=501×5,
=2505.
(1)
| 8 |
| 9 |
| 3 |
| 4 |
| 23 |
| 16 |
| 7 |
| 8 |
=
| 8 |
| 9 |
| 3 |
| 4 |
| 9 |
| 16 |
=
| 8 |
| 9 |
| 3 |
| 16 |
=
| 1 |
| 6 |
(2)9
| 1 |
| 5 |
| 1 |
| 5 |
| 1 |
| 5 |
| 1 |
| 5 |
| 4 |
| 5 |
=(9+
| 1 |
| 5 |
| 1 |
| 5 |
| 1 |
| 5 |
| 1 |
| 5 |
| 4 |
| 5 |
=(9+99+999+9999)+(
| 1 |
| 5 |
| 1 |
| 5 |
| 1 |
| 5 |
| 1 |
| 5 |
| 4 |
| 5 |
=9+99+999+9999,
=(10-1)+(100-1)+(1000-1)+(10000-1),
=(10+100+1000+10000)-(1+1+1+1),
=11110-4,
=11106;
(3)18÷[
| 5 |
| 6 |
| 5 |
| 8 |
| 1 |
| 3 |
=18÷[
| 5 |
| 6 |
| 7 |
| 24 |
=18÷
| 9 |
| 8 |
=16;
(4)
| 1 |
| 4 |
=0.25×2003+2005×0.25+2004×(0.25×3),
=0.25×(2003+2005+2004×3),
=0.25×2004×5,
=501×5,
=2505.
点评:此题主要考查分数、小数的四则混合运算的运算顺序和应用运算定律进行简便计算.
练习册系列答案
相关题目