Exhibit 11 EASTERN BANCORP, INC. Computation of Primary and Fully Diluted Earnings Per Share Three Months Ended December 31, (Dollars in thousands, except per share data) 1996 1995 --------- ---------- Net Income $1,421 $1,487 --------- ---------- --------- ---------- PRIMARY: Shares: Weighted average number of common shares outstanding 3,685,212 3,597,711 Dilutive effect of outstanding stock options 203,678 187,020 --------- ---------- Weighted average number of common and common equivalent shares 3,888,890 3,784,731 --------- ---------- --------- ---------- Earnings per share $0.37 $0.39 --------- ---------- --------- ---------- ASSUMING FULL DILUTION: Shares: Weighted average number of common shares outstanding 3,685,212 3,597,711 Fully diluted effect of outstanding stock options 217,468 202,225 --------- ---------- Weighted average number of common and common equivalent shares 3,902,679 3,799,936 --------- ---------- --------- ---------- Earnings per share $0.36 $0.39 --------- ---------- --------- ---------- 18