Suppose my birthdate is mm-dd-yyyy ( month-day-year).
If you take 2 digits out of these 8 digits and add them up , you will get 1,2,3,4,8,9,10,11,16 and 17 as the sums.(For example, if my birthdate had been 06-23-1975 , then you would have got 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 and 16 as the sums)
Further , dd can be expressed as the difference of the squares of two different positive integers in two different ways.
I was born in a non-leap year in the 20th century.