<P> A DEA number (DEA Registration Number) is an identifier assigned to a health care provider (such as a physician, optometrist, dentist, or veterinarian) by the United States Drug Enforcement Administration allowing them to write prescriptions for controlled substances . </P> <P> Though there is no legal basis for preventing its use as a general prescriber identification number, for security reasons the DEA prefers that DEA registration numbers only be used for authenticating and tracking prescriptions for controlled substances . The agency prefers that the National Provider Identifier be used for general identification purposes . </P> <P> A valid DEA number consists of: </P> <Ul> <Li> 2 letters, 6 numbers, and 1 check digit </Li> <Li> The first letter is a code identifying the type of registrant (see below) </Li> <Li> The second letter is the first letter of the registrant's last name, or "9" for registrants using a business address instead of name . </Li> <Li> Of the seven digits that follow, the seventh digit is a "checksum" that is calculated similarly to the Luhn algorithm, with the following steps: <Ul> <Li> Add together the first, third and fifth digits call this CALC </Li> <Li> Add together the second, fourth and sixth digits and multiply the sum by 2, call this CALC </Li> <Li> Add CALC + CALC call this CHECK </Li> <Li> The rightmost digit of CHECK (the digit in the ones place) is used as the check digit in the DEA number </Li> </Ul> </Li> </Ul>

A nurse practitioner will have a dea number starting with which of the following letters