Of the following DEA numbers, which one is valid?

Following the steps below, the sum at the end of step 4 is 56, and so the last digit of the DEA number must be 6 to be considered a valid DEA number.
Step 1: Add the first, third, and fifth numbers together ( 2 + 6 + 8 =16).
Step 2: Add the second, fourth, and sixth numbers together (4 + 7 + 9=20).
Step 3: Multiply the sum in the second step by 2 (20 x 2 =40).
Step 4: Add the total from steps 1 and 3 together (40 +16 =56).
Please note that there are ongoing revisions in the letters that can appear first in a DEA number. Changes have been made over the years to accommodate the increasing number of practitioners. *C, as well as other letters, can now be the first letter and is usually used for specialists rather than general practitioners.*