My social security card slid behind the desk at home and I am unable to get it out. I needed my card the other day and fortunately the local social security office was able to "verify" my number for me on the spot, but printing out a form and signing it for me. This was faster than getting a replacement card.
All I had to do was bring in my driver's license and my number. The lady asked me what my middle initial stood for and what my mother's maiden name was. Both were answered easily and I got my form and left.
I asked about my deceased grandmother's number, which is very close to mine. Her response to that question was "we aren't going to go there" probably because of concerns about fraud. The only thing she would tell me is the month and year my number was issued.