The question looks really simple, all I want to do is find the minimum number out of the 3 column values of a list item. Let me know if there is a way to achieve this either with Nintex workflow or Nintex forms.
Does this need to occur after the item is created? Or before the item is created an on the form? What do you want to do with this information?
If the item exists, and a workflow starts, then it can determine the smallest number of the 3 columns and email the user doing the following
You can do what ever you want instead of send email, maybe update a 4th column with the result. I'll see if there is an easier math operation, but this seemed like a quick answer.