题目内容

计算下列各题,能简算的要简算
7
8
×
1
12
+
1
8
÷12
(
5
8
+
3
4
-
1
2
)
×50%
15
28
÷
3
7
7
9
÷
11
5
+
2
9
×(
2
11
+
3
11
)
4
5
×37.5%×
1
9
1
12
+0.75×
2
3
÷2
分析:(1)把除法变为乘法,运用乘法分配律简算;
(2)把百分数化为分数,先算括号内的,再算括号外的;
(3)把除法变为乘法,约分计算;
(4)先算除法和括号内的,然后运用乘法分配律简算;
(5)把百分数化为分数,约分计算;
(6)把百分数化为分数,先算乘法,然后从左往右依次运算.
解答:解:(1)
7
8
×
1
12
+
1
8
÷12
=
7
8
×
1
12
+
1
8
×
1
12

=(
7
8
+
1
8
)×
1
12

=1×
1
12

=
1
12


(2)(
5
8
+
3
4
-
1
2
)×50%
=(
5
8
+
3
4
-
1
2
)×
1
2

=
7
8
×
1
2

=
7
16


(3)
15
28
÷
3
7

=
15
28
×
7
3

=
3
4


(4)
7
9
÷
11
5
+
2
9
×(
2
11
+
3
11

=
7
9
×
5
11
+
2
9
×
5
11

=(
7
9
+
2
9
)×
5
11

=1×
5
11

=
5
11


(5)
4
5
×37.5%×
1
9

=
4
5
×
3
8
×
1
9

=
1
30


(6)
1
12
+0.75×
2
3
+2
=
1
12
+
3
4
×
2
3
+2
=
1
12
+
1
2
+2
=2
7
12
点评:此题考查了分数的四则混合运算,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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