Hi SAS users.  Thank you so much for discussing this matter with me. After struggling for a whlie, I might have found out a solution that works ok. I used a dataset which I don't really like as it can be messy but it seemed to me that this way suited the problem.   I am presenting this for those who are interested. Let me know if you find any bugs   Basically, my code executes the following: 1. Takes each digit of the a character and converts it to a number (where digit1 is the 1 st digit from the right) 2. Add to the 1st, 2nd and the 3rd digit the required seed 3, 6 and 2, respectively. 3. Identify if any of the digit, starting the 1st digit if they are over 10, subtract by 10 then add 1 to the "carryover" value for the next digit. 4. Keep doing this until the end of the number then in the last do loop, concatenate each seeded digit. 5. drop any intermediate values used in this process. 6. I did not find any values with error=1 (indicating the seeded number will go over 32 digit) as the original IDs luckily but if you do have sufficiently large numbers such as (999999999.....999) it may well do and this is one limitation of my code.     data output; format e_ID $32.; set input; ARRAY digit {32} digit1-digit32; ARRAY result {32} result1-result32; ARRAY carryover {32} carryover1-carryover32; /* Intialise the elements of the arrays */ DO i=1 TO length(ID); digit{i}=input(substr(strip(ID),length(ID)-i+1,1),1.); result{i}=0; carryover{i}=0; END; DO i=1 TO length(ID); if i=1 then do; result{i}=sum(digit{i},3); if result{i}>9 then do; result{i}=result{i}-10; carryover{i+1}=1; end; end; else if i=2 then do; result{i}=sum(digit{i},6,carryover{i}); if result{i}>9 then do; result{i}=result{i}-10; carryover{i+1}=1; end; end; else if i=3 then do; result{i}=sum(digit{i},2,carryover{i}); if result{i}>9 then do; result{i}=result{i}-10; carryover{i+1}=1; end; end; else if 4<=i and i<=length(ID)-1 then do; result{i}=sum(digit{i},carryover{i}); if result{i}>9 then do; result{i}=result{i}-10; carryover{i+1}=1; end; end; if i=length(ID) then do; result{i}=sum(digit{i},carryover{i}); if result{i}>9 then do; error=1; end; end; END; DO i=1 TO length(ID); e_ID=strip(put(result{i},1.))||strip(e_ID); END; drop digit1--digit32 result1--result32 carryover1--carryover32error i; run;     ... View more