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Comment by sam_lowry_

20 hours ago

Belgian National Number is your birth date, then an increment from 1 to 999 for every baby born that day, then a base-97 checksum.

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sam_lowry_

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andruby  20 hours ago

Not sure if still the case: odd numbers for males and even numbers for females.

This also means a person’s Belgian RRN can change.

  • sam_lowry_  19 hours ago

    Yep, but they do not change on sex change, IIRC.

    • andruby  9 hours ago

      I wrote a system for a medical lab decades ago and IIRC I did actually have to change some RRN's manually. It's been a while so I'm not 100% sure, but I do think the changes were due to switching gender.