1/9+1/99+1/999+1/9999+1/99999=0.111...+0.0111...+0.00111...+0.000111...+0.0000111...=0.123455.=0.1234+0.00005555...=0.1234+0.00005555...=0.1234+5/90000=1234/10000+1/18000=22212/180000+10/180000=22222/...