How do I make a field auto-populate if a text field is entered to add 5 to a different Read Only field?

This is what I am working with. Sorry for not being clear.

I have 10 sections under the where the major and minor programs are just like this. I want to be able to calculate # of Sales days worked this week which would be 5 days per each section. So if every

section is filled out that number should total 50. The only problem I am having is not every section will be filled out. And I am not sure how to get it to auto calculate.

You're going to have to provide more details and describe exactly how you want this to behave. Your question and following statement is confusing to me.