REM Iterative solution
FUNCTION gcdI(x, y)
    DO WHILE y > 0
       LET t = y
       LET y = remainder(x, y)
       LET x = t
    LOOP
    LET gcdI = x
END FUNCTION

LET a = 111111111111111
LET b = 11111
PRINT
PRINT "GCD(";a;", ";b;") = "; gcdI(a, b)
PRINT
PRINT "GCD(";a;", 111) = "; gcdI(a, 111)
END