早教吧 育儿知识 作业答案 考试题库 百科 知识分享

脱式计算.(能简算的要简算)4013×39×780;65×23÷15;(34+45)×20;710÷9+310×19;(15-215)×30.

题目详情
脱式计算.(能简算的要简算)
40
13
×39×
7
80
;     
6
5
×
2
3
÷
1
5
;         (
3
4
+
4
5
)×20;        
7
10
÷9+
3
10
×
1
9
;    (
1
5
-
2
15
)×30.
▼优质解答
答案和解析
(1)
40
13
×39×
7
80

=120×
7
80

=
21
2


(2)
6
5
×
2
3
÷
1
5

=
4
5
÷
1
5

=4;

(3)(
3
4
+
4
5
)×20
=
3
4
×20+
4
5
×20
=15+16
=31;

(4)
7
10
÷9+
3
10
×
1
9

=
7
10
×
1
9
+
3
10
×
1
9

=(
7
10
+
3
10
)×
1
9

=1×
1
9

=
1
9


(5)(
1
5
-
2
15
)×30
=
1
5
×30-
2
15
×30
=6-4
=2.