Counting Numbers

## simple program to convert any number from digits to english spellings
## Works for 0 to billion-1
#TODO add argparse

def toWords(num):
    #Converts numbers from 0 to 999 to words
    #
    #

    op = ""
    if num > 999 or num < 0:
        op += "invalid"
        return
    if num == 0:
        op = numbers[0]
        return

    numbers = ['zero', 'one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine']
    teens = ['ten', 'eleven', 'twelve', 'thirteen', 'fourteen', 'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen']
    tens = [ '', 'ten', 'twenty', 'thirty', 'forty', 'fifty', 'sixty', 'seventy', 'eighty', 'ninty', 'hundred' ]
    powers = ['hundred', 'thousand', 'million']

    szNum = "%03d" % num
    if int(szNum[0]) != 0:      #Dxx
        op = numbers[int(szNum[0])] + " " + powers[0]

    if (szNum[0]!='0') & (szNum[1:3] != '00'):
        op += " and"

    if int(szNum[1]) == 1:      #1D
        if op != "":
            op += " "
        op = op + teens[int(szNum[1:3])-10]
        return op

    elif szNum[1] != '0':       #Dx
        if op != "":
            op += " "
        op = op + tens[int(szNum[1])]
    if szNum[2] != '0':         #xD
        if op != "":
            op += " "
        op += numbers[int(szNum[2])]
    return op


def getNumber(num):
    #converts numbers from 0 to 999,999,999 (ie 1billion-1)
    # to words.
    # useds toWords() to spell out chunks of 3 digit nums.

    powers = ['hundred', 'thousand', 'million']
    if num > 999999999:
        return "number too big"

    lower = num%1000
    thous = num//1000
    mills = thous//1000
    thous = thous%1000

    fo = ""
    if mills != 0:
        fo += toWords(mills) + " " + powers[2]

    if thous != 0:
        if fo != "":
            fo += " "
        fo += toWords(thous) + " " + powers[1]

    if lower != 0:
        if fo != "":
            fo += " "
        fo += toWords(lower)
    if num == 0:
        fo = "zero"
    return fo


for i in range(0,1999999, 91):
    print( str(i) + ": " + getNumber(i))