Page 95 Exhibit 11 NATIONAL SERVICE INDUSTRIES, INC. AND SUBSIDIARIES COMPUTATIONS OF NET INCOME PER SHARE OF COMMON STOCK (In thousands, except per-share data) THREE MONTHS ENDED NOVEMBER 30 1996 1995 Primary: Weighted Average Number of Shares (determined on a monthly basis) ................ 45,957 48,343 Net Income ....................................... $ 24,834 $ 23,269 Primary Earnings per Share ....................... $ .54 $ .48 Fully Diluted: Weighted Average Number of Shares Outstanding .................................... 45,957 48,343 Additional Shares Assuming Exercise of Options: Options exercised ............................ 1,204 1,233 Treasury stock purchased with proceeds ....... (947) (979) Average Common Shares Outstanding (as adjusted) ................................. 46,214 48,597 Net Income ....................................... $ 24,834 $ 23,269 Fully Diluted Earnings per Share ................. $ .54 $ .48