Hi,

I have a field (soc. security number) that is 13 digits long and have this structure

ddmmyyy45xxxc

where

dd - day of birth
mm - month of birth
yyy - year of birth without leading 1,2 (ex. 1965 - 965; 2002 = 002.....)
xxx - number from birth registry book (from 000-499 for mail 500-999 for female)

c - control digit by mod13 rule

how to calculate if entered value is corect by mod 13 rule.

Few sample soc.security numbers

2607974450185
1109955455024
0805963450018
2611961455029
2411974450078

Thanks,
Vladimir