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Business::PT::BI - Validate Portuguese BI (Bilhete de Identidade)


Version 0.01


    use Business::PT::BI;

    if ( valid_bi($bi, $control_number) ) {
      # ...



Validates Portuguese BI's.

A Portuguese BI number is comprised by eight digits. Between that number and the "issue" box, the card also has a small box with a single digit. That's the control digit. In order to validate a Portuguese BI, you have to provide valid_bi with the BI number and the control digit.

  valid_bi( $bi, $control_number );

Validation is done as follows:

 1) BI is matched with /^\d{8}$/ (eigth consecutive digits with
    nothing more)
 2) First digit is multiplied by 9, second by 8, third by 7, fourth by
    6, fifth by 5, sixth by 4, seventh by 3, eighth by 2
 3) All the results of the multiplication are summed
 4) Modulo of the sum by 11 is found
 5) Complement of the sum by 11 is found
 6) Control digit is compared to said complement

Example for BI 12345678, with control digit 9:

 1) BI is matched with /^\d{8}/, test passes
 2) Multiplication: 1*9, 2*8, 3*7, 4*6, 5*5, 6*4, 7*3, 8*2
 3) Sum: 156
 4) 156 % 11 = 2
 5) 11 - 2 = 9
 6) 9 == 9, test passes

When the complement (the result of step 5) is greater than 9, the number is assumed to be 0.


Jose Castro, <cog at>


Please report any bugs or feature requests to bug-business-pt-bi at, or through the web interface at I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.


You can find documentation for this module with the perldoc command.

    perldoc Business::PT::BI

You can also look for information at:


Copyright 2005 Jose Castro, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.