Has anyone figured out how to zero fill field using a custom formula where the field has to be a certain length, zero filled to that length, if the field value is shorter?

I would think the custom field would look different depending on if its a numeric or a text field.

for example:

field value : 345 (numeric)
fixed length: 7
right justified

will have to look like this:

0000345

field value: 34523

will have to look like this:

0034523

replace(right(space(x) + totext({field}, x), x)," ", "0")

as another idea...