HILLS BANCORPORATION EXHIBIT 11 COMPUTATION OF EARNINGS PER COMMON SHARE Three months ended Nine months ended September 30 September 30 ----------------------- ------------------------ 2002 2001 2002 2001 --------------------------------------------------- Weighted average number of shares outstanding (basic) ........... 1,499,108 1,498,053 1,498,723 1,496,438 Weighted average of potential dilutive shares attributable to stock options granted computed under the treasury stock method 13,145 12,674 13,259 12,248 Weighted average number of shares (diluted) .............. 1,512,253 1,510,727 1,511,982 1,508,686 Earnings Per Share: Net income (in thousands) ..... $ 3,236 $ 2,680 $ 8,532 $ 7,521 Earnings per common share: Basic ....................... $ 2.15 $ 1.79 $ 5.69 $ 5.02 Diluted ..................... $ 2.14 $ 1.77 $ 5.64 $ 4.98 1