计算:1-5/6+7/12-9/20+11/30-13/42+15/56-17/72=_.

问题描述:

计算:1-

5
6
+
7
12
-
9
20
+
11
30
-
13
42
+
15
56
-
17
72
=______.

1-

5
6
+
7
12
-
9
20
+
11
30
-
13
42
+
15
56
-
17
72

=1-(
1
2
+
1
3
)+(
1
3
+
1
4
)-(
1
4
+
1
5
)+(
1
5
+
1
6
)-(
1
6
-
1
7
)+(
1
7
-
1
8
)-(
1
8
-
1
9
),
=1-
1
2
+
1
9

=
1
2
+
1
9

=
11
18

故答案为:
11
18