(I) ABCD + EFGH = KLBK
: - +
(II) LL + EFFC = EFDL
----------------------
(III) EGA * AH = DGFG
(IV) (V) (VI)
(II.1) C = 0
(V.2) G = F + A
(II.2) D = F + L
(I.2) B = G + 1
(IV.1) L * A == D (mod 10) so L >= 2.
Assume E >= 2 then E*L<=6<=A from (IV).
Further A+E<=8<=K from (I) and K+E<=10<=D.
Therefore E = 1.
(VI.1) G == K + L
(VI.3) G == F + L + 1 there must be a carry otherwise K=F.
So K = F + 1 and G = D + 1 and then A = L + 1
(I.4) A + 1 <= K <= A + 2
So K = A + 2 otherwise F=A. That is F = A + 1.
3806 + 1479 = 5285
: - +
22 + 1440 = 1462
----------------------
173 * 39 = 6747