FUNCTION romToDec (roman$)
    num = 0
    prenum = 0
    FOR i = LEN(roman$) TO 1 STEP -1
        x$ = MID$(roman$, i, 1)
        n = 0
        IF x$ = "M" THEN n = 1000
        IF x$ = "D" THEN n = 500
        IF x$ = "C" THEN n = 100
        IF x$ = "L" THEN n = 50
        IF x$ = "X" THEN n = 10
        IF x$ = "V" THEN n = 5
        IF x$ = "I" THEN n = 1

        IF n < preNum THEN num = num - n ELSE num = num + n
        preNum = n
    NEXT i

    romToDec = num
END FUNCTION

!Testing
PRINT "MCMXCIX = "; romToDec("MCMXCIX")     '1999
PRINT "MDCLXVI = "; romToDec("MDCLXVI")     '1666
PRINT "XXV     = "; romToDec("XXV")         '25
PRINT "CMLIV   = "; romToDec("CMLIV")       '954
PRINT "MMXI    = "; romToDec("MMXI")        '2011