How can I calculate values in a column?

If you want to perform a calculation inside of a form, please check this guide:

How to Perform Form Calculation Using a Widget

If you have an Input Table inside of a form, then check this guide as well:

How to Perform Form Calculation in the Matrix Field?

If I did not understand your question correctly, please explain in more details what are you trying to achieve and provide us a link of a form you are working on.