Maybe, in function Thirt, you should set result and tempPrevResult without call recursiveCalculation?

func Thirt(n int) int {
  // set initial value of result
  result = n
  // iterating until condition met
  for result != tempPrevResult {
    recursiveCalculation(result)
  }
  return result
}

I just did this GO katas during my introduction to language, so for sure it is not a best practice. People just express their oppinions by giving these upvotes, don't take them as something serious.
Good luck on your journey with Go, since I've lost interest to it pretty quick.

Yeah, you are right I should have make it recursive if I called it this way.

recursiveCalculation function is not a recursive function since it doesn't call itself to solve the solution but get called multiple times from the outside

Great solution. Clear, succinct, clever.
Sad that i didn't come up with solution using Stack

This one is from an experinced developer for sure! I laughed at first, but then i changed my oppinion. Nice one dude.

Converting integer to string back and forth just to get last digit...
In NO WAY this is "best practices".

Pretty neat solution you've comed up with.