1/2+5/6+11/12+19/20+29/30+…+9701/9702+9899/9900.

问题描述:

1
2
+
5
6
+
11
12
+
19
20
+
29
30
+…+
9701
9702
+
9899
9900

1
2
+
5
6
+
11
12
+
19
20
+
29
30
+…+
9701
9702
+
9899
9900

=(1-
1
2
)+(1-
1
6
)+(1-
1
12
)+…+(1-
1
9900

=1×99-(
1
2
+
1
6
+
1
12
+…+
1
9900
),
=99-(
1
1×2
+
1
2×3
+
1
3×4
…+
1
99×100
),
=99-(1-
1
2
+
1
2
-
1
3
+
1
3
1
4
+…+
1
99
-
1
100
),
=99-(1-
1
100
),
=99-
99
100

=98
1
100