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 SIX MONTHS ENDED FEBRUARY 28 FEBRUARY 28 1995 1994 1995 1994 Primary: Weighted Average Number of Shares (determined on a monthly basis) 48,859 49,572 49,025 49,568 Net Income $17,578 $16,273 $38,692 $35,445 Primary Earnings per Share $ .36 $ .33 $ .79 $ .72 Fully Diluted: Weighted Average Number of Shares Outstanding 48,859 49,572 49,025 49,568 Additional Shares Assuming Exercise of Options: Options exercised 691 745 691 745 Treasury stock purchased with proceeds (606) (637) (606) (637) Average Common Shares Outstanding (as adjusted) 48,944 49,680 49,110 49,676 Net Income $17,578 $16,273 $38,692 $35,445 Fully Diluted Earnings per Share $ .36 $ .33 $ .79 $ .71