How can I make it so the user can only add the last 4 digits of a socia

How can I make it so the user can only add the last 4 digits of a social security number?

Example:

The users social security number is:

123-45-6789

The field should look like this:

###-##-_ _ _ _

When they type in the last 4 digits only, numbers on the screen turns into a # but in the email you can see the last 4 digits.

Is this possible?

Use a character that is not #, @ or *. In my example below, I used the "X" character as the masked input so user will just need to input the last four digit of their SSN.

I hope this helps. Let us know if you have any questions or if you need further assistance.