(I) ABCD : EE = EFD + + * (II) GHEH - GIKC = IF ---------------------- (III) HHDI + GICF = DBCA (IV) (V) (VI) Solution: (III) D != 0 (III.2) D = 9 (IV.3) B = 0 (I.1) 9 == 9E (mod 10) => E = 1 (I) A = 2 as 30 : 11 > 2. (VI.1) 2 == 9F == -F (mod 10) => F = 8 (V.1) C = 7 (III.1) I = 4 (IV.1) H = 5 (IV.4) G = 3 (V.2) K = 6 2079 : 11 = 189 + + * 3515 - 3467 = 48 ---------------------- 5594 + 3478 = 9072 References: Hoer Zu, No 53, 2004, 2004-12-22