# stdnum.casrn

CAS RN (Chemical Abstracts Service Registry Number).

The CAS Registry Number is a unique identifier assigned by the Chemical Abstracts Service (CAS) to a chemical substance.

More information:

- https://en.wikipedia.org/wiki/CAS_Registry_Number

    >>> validate('87-86-5')
    '87-86-5'
    >>> validate('87-86-6')
    Traceback (most recent call last):
        ...
    InvalidChecksum: ...

`stdnum.casrn.``calc_check_digit`(number)

  Calculate the check digit for the number. The passed number should not have the check digit included.

`stdnum.casrn.``compact`(number)

  Convert the number to the minimal representation.

`stdnum.casrn.``is_valid`(number)

  Check if the number provided is a valid CAS RN.

`stdnum.casrn.``validate`(number)

  Check if the number provided is a valid CAS RN.