HILLS BANCORPORATION EXHIBIT 11 COMPUTATION OF EARNINGS PER COMMON SHARE Three months ended March 31, 2000 1999 -------------------------- Weighted average number of shares outstanding (basic) ........................ 1,495,941 1,470,322 Weighted average of potential dilutive shares attributable to stock options granted computed under the treasury stock method ............................... 12,585 24,516 --------------------------- Weighted average number of shares (diluted) .................................. 1,508,526 1,494,838 =========================== Earnings Per Share: Net income (in thousands) .................. $ 2,204 $ 2,079 =========================== Earnings per common share: Basic .................................... $ 1.47 $ 1.41 =========================== Diluted .................................. 1.46 1.39 ===========================