Date calculation

[Dado]

I want to resolve date calculation problem.

I have one form field with users total sum of lenght of service (format of field looks like yy/mm/ddd) in another form field I have data with users date of employment in a firm.
In the third field I want to show total sum of lenght of service (previouse lenght of service and lenght of service in our firm) in format like in first field yy/mm/ddd.

What is a easiest way to calculate a third field in a form.

Thanks in advance !!

 

[RuralGuy]

Are all the controls on the same form? Are they all bound to fields in a query/table? What DataTypes are we dealing with, text? What does the ddd stand for?

 

[Dado]

Yes all controls (fields)are on the same form.They are bound to one table.
ddd stands for days.For example some user have 12/11/123 lenght of service or 12 years/11 months/123 days (so format of control is text), I now that I cant calculate controls with date and text together.
This is new controls in my form I dont use them before, so this is reason why I looking for help to solve this problem with users lenght of service.

Thanks

 

[RuralGuy]

Controls are on forms and fields are in tables/queries just for the reference. You can bind controls to fields. Are the fields in the table/query text fields. Why would you ever have more than 31 days? 12 years/11 months/123 days does not make much sense to me since you can just bump the years and months until days is less than 32. I'm working on a function that will add things for you while I'm asking questions.