Script needed

I have a multi part form which calls for the social security number in multiple places. In some places it is entered as normal but in others each digit is it's own field.

So, I would like to be able to type the socail normally i.e. 123-45-6789 but have each number fill a dedicated field elsewhere in the form i.e. [][][]-[][]-[][][][] So, each number will fill each of those boxes.

Any help writing a script like taht would be appreciated.