What was Ty Cobbs number while he was with the Detroit Tigers?

Four teams have honored players who played before the advent of uniform numbers by placing their names among those of players whose numbers have been retired:

Detroit Tigers: Ty Cobb, Mickey Cochrane, Sam Crawford, Harry Heilmann, Hughie Jennings, George Kell, Heinie Manush; Cobb's name is displayed on the left-field wall of Comerica Park along with the players and manager whose numbers have been retired; the others have their names displayed on the right-field wall (Cochrane actually wore #3 for the Tigers, and Kell wore three different numbers, but the Tigers have not retired these numbers)