先观察,然后想一想其中的规律.再计算.
1 1 1 1
--------- = ------- = ------ — -----
2×3 6 2 3
1 1 1 1
--------- = ------- = ------ — -------
3×4 12 3 4
1 1 1 1
--------- = ------- = ------ — -------
4×5 20 4 5
1 1 1 1
计算：---------- + ------------ + --------------····················------------
2×3 3×4 4×5 99×100