The SL NIC could be divided into two groups,
NICs issued before 1 January 2016, each NIC has a unique 9-digit number and a letter, in the format 000000000V (where 0 is a digit and V is a letter). The first two digits of the number are the holder's year of birth (e.g.: 91xxxxxxxx for someone born in 1991). The next three digits contain the number of the day in the year for the person's birth. For females, 500 is added to the number of days. The next three digits number is the serial number of the issued day. The next digit is the check digit. The final letter is generally a 'V' which indicates that the holder is eligible to vote in the area. In some cases the final letter can be 'X' which usually indicates the holder is not eligible to vote; possibly because they were not permanent residents of Sri Lanka when applying for a NIC. (Directly copied from Wikipedia)
Birth Year: 72 Day Count for Birthday: 244 Serial Number; 152 Check Digit: 4 Special Letter: V
The NIC Number: 722441524V
Birth Year: 2001 Day Count for Birthday: 253 Serial Number; 0297 Check Digit: 6 Special Letter: -
The NIC Number: 200125302976