NUMBERS (CBS) - Alimi Ballard ("Dark Angel") is the latest to join the cast of the drama pilot, which revolves around two brothers, one in the F.B.I. (Gabriel Macht) and the other an M.I.T. math whiz (David Krumholtz), who team up to fight crime. Ballard will play David, a young F.B.I. agent, in the Paramount Network Television project, which comes from executive producers Cheryl Heuton, Nick Falacci, Ridley Scott and Tony Scott.