How to display blanks instead of zeros for numbers in BIP

I am working to customize a check stub for our company and cannot figure out how to get a number field to default to blank instead of zeros.  I would have thought that going into the properties of the field and setting default value to a space would do the trick but it still displays zeros.  Another thought I had was to change the font color to white conditionally but could not figure that out either.  Could somebody point me in the right direction?

Thank you,

Jim