How do you know if a oil painting is numbered?

I HAVE A OIL PAINTING BY J MARIN IT LOOKS LIKE A Q AFER THAT ITS NUMBERED 9/24 0N BACK, ITS CANVAS STAPLED I NEED TO KNOW WHO ARTIST IS WHAT THE NUMBER MEANS, AND IS IT OLD, THE PAINTING LOKSVERY OLD BUT NOT FRAME. CAN ANY ONE HELP ME DONT KNOW WHO ARTIST IS.