题目内容
用简便方法计算下列各题
25
|
|
|
|
| ||||||||||||||||||||||||||
(
|
|
3
|
36×
|
(
|
考点:分数的简便计算
专题:运算定律及简算
分析:(1)把带分数拆成“整数+分数”的形式,运用乘法分配律简算.
(2)运用乘法交换律与结合律简算.
(3)(5)(7)(10)运用乘法分配律简算.
(4)先算除法,再从左往右依次计算.
(6)先算括号内的,再算括号外的.
(8)把带分数化为假分数,约分计算.
(9)把36看作35+1,运用乘法分配律简算.
(2)运用乘法交换律与结合律简算.
(3)(5)(7)(10)运用乘法分配律简算.
(4)先算除法,再从左往右依次计算.
(6)先算括号内的,再算括号外的.
(8)把带分数化为假分数,约分计算.
(9)把36看作35+1,运用乘法分配律简算.
解答:
解:(1)25
×8
=(25+
)×8
=25×8+
×8
=200+3
=203
(2)
×(15×
)×
=(
×
)×(15×
)
=
×2
=
(3)
×101-
=
×(101-1)
=
×100
=70
(4)
×
÷
×
=
×(
÷
)×
=
×
=
(5)
×99+
=
×(99+1)
=
×100
=60
(6)(
+
)×
=
×
=
(7)
×
+
×
-
=(
+
-1)×
=
×
=
(8)3
×25
=
×25
=95
(9)36×
=(35+1)×
=35×
+
=34+
=34
(10)(
-
)×
=
×
-
×
=3-2
=1
3 |
8 |
=(25+
3 |
8 |
=25×8+
3 |
8 |
=200+3
=203
(2)
2 |
27 |
27 |
28 |
2 |
15 |
=(
2 |
27 |
27 |
28 |
2 |
15 |
=
1 |
14 |
=
1 |
7 |
(3)
7 |
10 |
7 |
10 |
=
7 |
10 |
=
7 |
10 |
=70
(4)
8 |
9 |
8 |
9 |
8 |
9 |
8 |
9 |
=
8 |
9 |
8 |
9 |
8 |
9 |
8 |
9 |
=
8 |
9 |
8 |
9 |
=
64 |
81 |
(5)
3 |
5 |
3 |
5 |
=
3 |
5 |
=
3 |
5 |
=60
(6)(
4 |
7 |
8 |
9 |
2 |
25 |
=
92 |
63 |
2 |
25 |
=
184 |
1575 |
(7)
15 |
21 |
3 |
4 |
10 |
21 |
3 |
4 |
3 |
4 |
=(
15 |
21 |
10 |
21 |
3 |
4 |
=
4 |
21 |
3 |
4 |
=
1 |
7 |
(8)3
4 |
5 |
=
19 |
5 |
=95
(9)36×
34 |
35 |
=(35+1)×
34 |
35 |
=35×
34 |
35 |
34 |
35 |
=34+
34 |
35 |
=34
34 |
35 |
(10)(
5 |
6 |
5 |
9 |
18 |
5 |
=
5 |
6 |
18 |
5 |
5 |
9 |
18 |
5 |
=3-2
=1
点评:仔细分析数据,运用合适的简便方法计算.
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