Beretta 1915 Serial Number Info.

While going through my boxes of pieces and parts, I found remnants of a Beretta 1915. I can't seem to make out all of the SN. Seems that the numbers have been partially worn off over the decades.

1. How many numbers were on these?
2. Is there anything I can do to make the SN more ledgible?
3. Should I just not worry about it?

Thanks in advance.