Is it a good idea to put someones social security number on facebook?

[Common Sense]

Of course it is not a good idea to put anyone's social security number on a social network web site for all to see.

People are too free with information they give and over the course of time, putting all the facts together can cause drama in ones life unless they care careful about what they reveal for everyone to know.

Including this silly oversight about the SS number. I would have told her if she did not immediately delete the information, I would call her dad. This would have given her the opportunity to right the wrong without her dad even finding out about it. That would have been the right order to accomplish your goal of having that information removed.