问题 解答题
用简便方法计算下面各题.
2
7
×
4
5
+
5
7
×
4
5
5
9
×7+11÷
9
5
8
13
÷7+
1
7
×
5
13
15×
6
7
-
6
7
答案

(1)

2
7
×
4
5
+
5
7
×
4
5

=(

2
7
+
5
7
)×
4
5

=1×

4
5

=

4
5

(2)

5
9
×7+11÷
9
5

=

5
9
×7+11×
5
9

=

5
9
×(7+11)

=

5
9
×18

=10;

(3)

8
13
÷7+
1
7
×
5
13

=

8
13
×
1
7
+
1
7
×
5
13

=(

8
13
+
5
13
)×
1
7

=1×

1
7

=

1
7

(4)15×

6
7
-
6
7

=(15-1)×

6
7

=14×

6
7

=12.

单项选择题
单项选择题