题目内容
脱式计算,能简便的简便.
(1)123×5.67+8.77×567 | (2)22-
| ||||||||||
(3)299÷(299+
| (4)[
| ||||||||||
(5)0.125×0.25×32 | (6)9
|
考点:小数四则混合运算,运算定律与简便运算,整数、分数、小数、百分数四则混合运算
专题:运算顺序及法则,运算定律及简算
分析:(1)根据乘法分配律进行简算;
(2)先算乘法,再根据减法的性质进行简算;
(3)小括号里面根据乘法分配律进行简算,再根据除法的性质进行简算;
(4)中括号里面根据减法的性质进行简算,最后算乘法;
(5)根据乘法交换律和结合律进行简算;
(6)根据加法交换律和结合律进行简算.
(2)先算乘法,再根据减法的性质进行简算;
(3)小括号里面根据乘法分配律进行简算,再根据除法的性质进行简算;
(4)中括号里面根据减法的性质进行简算,最后算乘法;
(5)根据乘法交换律和结合律进行简算;
(6)根据加法交换律和结合律进行简算.
解答:
解:(1)123×5.67+8.77×567
=123×5.67+877×5.67
=(123+877)×5.67
=1000×5.67
=5670;
(2)22-
×
-
=22-
-
=22-(
+
)
=22-1
=21;
(3)299÷(299+
)
=299÷[299×(1+
)]
=299÷[299×
]
=299÷299÷
=1÷
=
;
(4)[
-(
+
)]×
=[
-
-
]×
=[1-
]×
=
×
=
;
(5)0.125×0.25×32
=0.125×0.25×(4×8)
=(0.125×8)×(0.25×4)
=1×1
=1;
(6)9
+99
+999
+9999
=(9+
+
+
)+99
+999
+9999
=9+(99
+
)+(999
+
)+(9999
+
)
=9+100+1000+10000
=109+1000+10000
=1109+10000
=11109.
=123×5.67+877×5.67
=(123+877)×5.67
=1000×5.67
=5670;
(2)22-
3 |
4 |
1 |
2 |
5 |
8 |
=22-
3 |
8 |
5 |
8 |
=22-(
3 |
8 |
5 |
8 |
=22-1
=21;
(3)299÷(299+
299 |
300 |
=299÷[299×(1+
1 |
300 |
=299÷[299×
301 |
300 |
=299÷299÷
301 |
300 |
=1÷
301 |
300 |
=
300 |
301 |
(4)[
13 |
8 |
5 |
8 |
5 |
7 |
3 |
4 |
=[
13 |
8 |
5 |
8 |
5 |
7 |
3 |
4 |
=[1-
5 |
7 |
3 |
4 |
=
2 |
7 |
3 |
4 |
=
3 |
14 |
(5)0.125×0.25×32
=0.125×0.25×(4×8)
=(0.125×8)×(0.25×4)
=1×1
=1;
(6)9
3 |
4 |
3 |
4 |
3 |
4 |
3 |
4 |
=(9+
1 |
4 |
1 |
4 |
1 |
4 |
3 |
4 |
3 |
4 |
3 |
4 |
=9+(99
3 |
4 |
1 |
4 |
3 |
4 |
1 |
4 |
3 |
4 |
1 |
4 |
=9+100+1000+10000
=109+1000+10000
=1109+10000
=11109.
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定律简便计算.
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