INPUT "vvedite 1 chislo ", a
INPUT "vvedite 2 chislo ", b
DO
k = k + 1
c1 = a MOD 10
c2 = b MOD 10
s = c1 + c2
PRINT "summa "; k; "-go razryada="; s
a = a \ 10
b = b \ 10
LOOP UNTIL a = 0 AND b = 0
Тестирование выполнено в программе QB64 ( Скачать )