Sum of values using column names

I’ve got that kind of scenario:
I’ll getting from outside an Excel where number of columns and rows will change everytime. Maximum numbers of columns it will be 25. For example I will get columns with price of Product1, Product2, Product3 once and another time only columns with prices of Product2 and Product3.
I would add column where I will have to keep sum of for example Product1+Product+Product3. How to get this sum using column names (not excel range) remember that sometimes column can not exist and how to keep this sum in new column which I create

So what i can think about this excel spread sheet you are getting has a common heading . You can convert this to data table once you import excel spread sheet to uipath and later using datatable activity or related activity you can solve this problem.