This module is used to generate the unique number and self check the numbers in social security, band accounts and etc.

Here you can find detailed explanation:
http://www.eclectica.ca/howto/modulus-11-self-check.php?start=1&count=5&generate=Generate#calculator

I have made this scirpt generate numbers in drop down list and write brojevi.txt file that you can download with numbers you have generated...