# stdnum.tr.vkn

VKN (Vergi Kimlik Numarası, Turkish tax identification number).

The Vergi Kimlik Numarası is the Turkish tax identification number used for businesses. The number consists of 10 digits where the first digit is derived from the company name.

More information:

- https://www.turkiye.gov.tr/gib-intvrg-vergi-kimlik-numarasi-dogrulama

    >>> validate('4540536920')
    '4540536920'
    >>> validate('4540536921')
    Traceback (most recent call last):
        ...
    InvalidChecksum: ...
    >>> validate('454053692')
    Traceback (most recent call last):
        ...
    InvalidLength: ...

`stdnum.tr.vkn.``calc_check_digit`(number)

  Calculate the check digit for the specified number.

`stdnum.tr.vkn.``compact`(number)

  Convert the number to the minimal representation. This strips the number of any valid separators and removes surrounding whitespace.

`stdnum.tr.vkn.``is_valid`(number)

  Check if the number is a valid Vergi Kimlik Numarası. This checks the length and check digits.

`stdnum.tr.vkn.``validate`(number)

  Check if the number is a valid Vergi Kimlik Numarası. This checks the length and check digits.