Page 14 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 1994 1993 1994 1993 Primary: Weighted Average Number of Shares (determined on a monthly basis) 49,572 49,558 49,568 49,552 Net Income $16,273 $14,634 $35,445 $33,220 Primary Earnings per Share $ .33 $ .30 $ .72 $ .67 Fully Diluted: Weighted Average Number of Shares Outstanding 49,572 49,558 49,568 49,552 Additional Shares Assuming Exercise of Options: Options exercised 745 567 745 567 Treasury stock purchased with proceeds (637) (478) (637) (478) Average Common Shares Outstanding (as adjusted) 49,680 49,647 49,676 49,641 Net Income $16,273 $14,634 $35,445 $33,220 Fully Diluted Earnings per Share $ .33 $ .29 $ .71 $ .67