Last 4 of your SSN?

Question

Why are these numbers the magic numbers into who you are? What do they really offer. I know that everyone has a different SSN. I know that each state of birth (or where you first filed for your SSN) has its own identifing number...and these are the first three numbers in your SSN...but are the last four the only different ones?? Can the first five really match someone else...does NO one else EVER in ANY other state EVER have the same last four? Just curious...

Answer 1

The last 4 numbers can be duplicated, but they are unlikely to be guessed, since there are 10,000 possible answers.  And most people know their SS# by heart.  

No one wants to give their full social security number any more due to identity theft.