Write your birth date or the birth date of someone in your family as
Write your birth date or the birth date of someone in your family as mm/dd/yy. (Example: March 13, 1981 is written 3/13/81, and November 7, 1967 is written 11/7/67).
Now let a = the one- or two-digit month number,
b = the negative of the one- or two-digit day number, and
c = the two-digit year number.
(Our example: a = 3, b = -13, and c = 81 or a = 11, b = -7, and c = 66)