1/6+1/12+1/20+1/30+1/42+1/56+1/72å¢ï¼
ï¼1-1/2ï¼Ãï¼1-1/3ï¼Ãï¼1-1/4ï¼Ãâ¦Ãï¼1-1/99ï¼Ãï¼1-1/100ï¼å¢ï¼
1/6+1/12+1/20+1/30+1/42+1/56+1/72
=1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8+1/8*9
=1/2-1/3+1/3-1/4+....+1/8-1/9
=1/2-1/9
=7/18
ï¼1-1/2ï¼Ãï¼1-1/3ï¼Ãï¼1-1/4ï¼Ãâ¦Ãï¼1-1/99ï¼Ãï¼1-1/100ï¼
=1/2*2/3*3/4*4/5*.......*98/99*99/100
=1/100