Bear Stearns Cos. told staffers yesterday that it will be cutting 830 jobs, or 7.5 percent of its work force. In a memo to employees, Chief Executive Officer James Cayne said the job cuts were necessary "to increase efficiency and eliminate duplication in our processes." Roughly 40 percent of the job reductions will come from investment banking and capital markets. The remaining cuts will come from administrative and information technology areas. The Post first reported the planned cuts at Bear Stearns on Oct. 10.