1/1×2+1/12+1/20+1/30...1/2005×2006

问题描述:

1/1×2+1/12+1/20+1/30...1/2005×2006

1-1/2+1/3-1/4+1/4-1/5+1/5-1/6+...+1/2005-1/2006=1/2+1/3-1/2006=2506/3009