MDDI recently stated that "people can make a good guess at someone's full NRIC number [...] especially if one also knows the year of birth of the person". I will attempt to make a good guess at Minister Josephine Teo's NRIC based on available information.
I will be working off this set of information
- Last 4 characters of her NRIC is 541B. Many establishments collect the last 4 characters of NRIC.
- Her date of birth is 8 July 1968. From Wikipedia.
- She was born in Singapore and a citizen at birth.
Most would know that anyone born before 2000 will have an NRIC starting with S. Also, anyone born after 1 Jan 1968 will have the birth year as the first 2 digits of the NRIC. Therefore, the partially reconstructed NRIC will look like
S68XX541B
Right off the bat, we are only missing 2 digits, hence there are only 100 possibilities. However, we can also narrow this down further, as the final character is a checksum using the Modulo 11 algorithm. Therefore, this leaves us with only 9 possibilities that end with the checksum B. NRICs are also issued sequentially, the first registered birth on Jan 1 1968 will be given S6800001G. Since there are 47,241 births in 1968, the last registered birth on 31st Dec 1968 will likely be S6847241E.
S6810541B
S6821541B
S6832541B
S6843541B
S6854541B --> There are only 47k births. Impossible to have 3rd digit of 5
S6865541B --> There are only 47k births. Impossible to have 3rd digit of 6
S6876541B --> 3rd digit 7 is issued to new citizens.
S6887541B --> 3rd digit 8 is likely invalid, or possibly reserved if number of new citizens overflow.
S6898541B --> 3rd digit 9 is issued to Singaporeans born overseas.
This leaves us with only 4 possible NRICs. Next, we will need to look at the number of births in each month in 1968. The data can be obtained from SingStat. Numbers in brackets are cumulative.
1968 Jan - 4016
1968 Feb - 3636 (7652)
1968 Mar - 3794 (11446)
1968 Apr - 3762 (15208)
1968 May - 3895 (19103)
1968 Jun - 3774 (22877)
1968 Jul - 3979 (26856)
1968 Aug - 4092 (30948)
1968 Sep - 4013 (34961)
1968 Oct - 4338 (39299)
1968 Nov - 3954 (43253)
1968 Dec - 3988 (47241)S6810541B --> 10541st registered birth. Occurred in Feb 1968.
S6821541B --> 21541st registered birth. Occurred in May 1968.
S6832541B --> 32541st registered birth. Occurred in Aug 1968.
S6843541B --> 43541st registered birth. Occurred in Dec 1968.
Assuming that the information we have earlier is accurate, Minister Josephine Teo's NRIC is likely to be either S6821541B or S6832541B. The latter seems slightly more promising because parents have up to 42 days to register the birth with ICA. However, it could also be the former. Back in 1968, there were more uneducated folks who may not have registered their child's birth timeously.
I'm not sure who started the practice of collecting the last 4 characters of NRIC. As shown, it allows others to narrow down the possibilities greatly especially if we have the approximate date of birth and citizenship information. Collecting the first 4 characters of NRIC is also not ideal as it reveals a person's age and citizenship information. Unfortunately, there are no easy solutions. We have inherited this system where NRIC numbers are issued sequentially instead of randomly, hence allowing this sort of data derivation to occur.