Thanks for your help for the Luhn algorithm, helped me a lot!
I have to check social security numbers, that contain 2 check digits, one LUHN10 and one VERHOEFF. I haven't found a solution for the Verhoeff checkdigit in SAS yet.The number to check is YYYY
MMDDXXXLV with L the luhn checkdigit based on the first 11 digits and V the verhoeff checkdigit based also on the first 11 digits.

Could anyone help please?

Thanks