Page 57 Exhibit 11 NATIONAL SERVICE INDUSTRIES, INC. AND SUBSIDIARIES COMPUTATIONS OF NET INCOME PER SHARE OF COMMON STOCK (In thousands, except per-share data) Years Ended August 31 1996 1995 1994 Primary: Weighted Average Number of Shares Outstanding (determined on a monthly basis) ........... 47,941 48,696 49,547 Net Income ..................................$101,148 $ 94,097 $ 82,698 Primary Earnings per Share ..................$ 2.11 $ 1.93 $ 1.67 Fully Diluted: Weighted Average Number of Shares Outstanding ............................... 47,941 48,696 49,547 Additional Shares Assuming Exercise of Options: Options exercised ....................... 1,260 989 707 Treasury stock purchased with ........... (919) (835) (619) Average Common Shares Outstanding (as adjusted) ............................ 48,282 48,850 49,635 Net Income ..................................$101,148 $ 94,097 $ 82,698 Fully Diluted Earnings per Share ............$ 2.09 $ 1.93 $ 1.67