题目内容
用简便方法计算下面各题.
÷7+
×
(
×
)÷
×20+
×20
(
-
+
)×30.
8 |
13 |
1 |
7 |
6 |
13 |
(
1 |
2 |
1 |
3 |
1 |
6 |
5 |
7 |
5 |
7 |
(
1 |
3 |
1 |
5 |
1 |
6 |
考点:分数的简便计算
专题:运算定律及简算
分析:(1)把除法变为乘法,运用乘法分配律简算.
(2)先算括号内的,再算括号外的.
(3)(4)运用乘法分配律简算.
(2)先算括号内的,再算括号外的.
(3)(4)运用乘法分配律简算.
解答:
解:(1)
÷7+
×
=
×
+
×
=(
+
)×
=
×
=
(2)(
×
)÷
=
÷
=1
(3)
×20+
×20
=(
+
)×20
=
×20
=
(4)(
-
+
)×30
=
×30-
×30+
×30
=10-6+5
=9
8 |
13 |
1 |
7 |
6 |
13 |
=
8 |
13 |
1 |
7 |
1 |
7 |
6 |
13 |
=(
8 |
13 |
6 |
13 |
1 |
7 |
=
14 |
13 |
1 |
7 |
=
2 |
13 |
(2)(
1 |
2 |
1 |
3 |
1 |
6 |
=
1 |
6 |
1 |
6 |
=1
(3)
5 |
7 |
5 |
7 |
=(
5 |
7 |
5 |
7 |
=
10 |
7 |
=
200 |
7 |
(4)(
1 |
3 |
1 |
5 |
1 |
6 |
=
1 |
3 |
1 |
5 |
1 |
6 |
=10-6+5
=9
点评:此题主要考查了分数的四则运算,根据数据特点,灵活简算.
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