1/1*6+1/6*11+1/11*16+...+1/106*111
=(1/1-1/6)/5+(1/6-1/11)/5+……+(1/106-1/111)/5
=(1-1/6+1/6-1/11+1/11-……+1/106-1/111)/5
=(1-1/111)/5
=22/111