Everyone knows that South African ID numbers start with date of birth. If you were born on May 13, 1988 then your ID number starts with 880513.

This post details what the rest of the digits in an ID number mean.

The format is:

{YYMMDD} {G} {SSS} {C} {X} {Z}

• {YYMMDD} is the date of birth
• {G} is gender. 0-4 is female and 5-9 is male
• {SSS} is a sequence number
• {C} is citizenship. 0 for South Africans and 1 for other citizens
• {X} is usually 8 or 9 – not clear what this is
• {Z} is a check digit calculated from the other digits

So for the ID number 8909025012083 we know certain things about the person:

• Born on September 2nd, 1989
• Male
• 12th male born on that date to get an ID number
• South African citizen

Not very useful, but interesting.