A CAS Registry number is a numeric identifier. It is a connection to an abundance of information on a chemical substance. It classifies just one substance and has no chemical importance.
The CAS Registry is a collection of disclosed chemical substance information. It has over 101 million organic and inorganic substances and 66 million sequences. A CAS Registry number can consist of up to 10 numbers divided into three parts by hyphens. The number farthest to the right is used as a check digit to substantiate the validity and uniqueness of the whole number. A substance is given a CAS Registry number when it is registered in the CAS Registry database.