Page 20 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 NINE MONTHS ENDED MAY 31 MAY 31 1996 1995 1996 1995 Primary: Weighted Average Number of Shares (determined on a monthly basis).. 48,059 48,382 48,240 48,813 Net Income ........................ $ 27,677 $ 25,627 $ 70,196 $ 64,319 Primary Earnings per Share ........ $ .58 $ .53 $ 1.46 $ 1.32 Fully Diluted: Weighted Average Number of Shares Outstanding ..................... 48,059 48,382 48,240 48,813 Additional Shares Assuming Exercise of Options: Options exercised ............. 1,293 1,031 1,293 1,037 Treasury stock purchased with proceeds ............... (919) (874) (919) (878) Average Common Shares Outstanding (as adjusted) .................. 48,433 48,539 48,614 48,972 Net Income ........................ $ 27,677 $ 25,627 $ 70,196 $ 64,319 Fully Diluted Earnings per Share .. $ .57 $ .53 $ 1.44 $ 1.31