The numbers are membership numbers in WBCCI...(Wally Byam Caravan Club International) ... According to the 2014 International Directory, #10275 is not currently in use (unless it has been re-assigned since the Directory was printed), so you can request that number when you join a unit. Go to WBCCI.org
website and find more info on units in your area (though you are not necessarily required to join a unit in your geographical area and can join any unit you wish)... I'd suggest attending a few unit's rallies as a guest to find a good fit for you. Then enjoy!