OOP vs Functional Programming for a calculator

Hello all!

I have a calculator project from TOP that I have been putting off in favor of polishing my algorithm knowledge and general syntax memorization. Now, I’m quite sure that I can complete the project, I wanted to ask your thoughts on whether OOP or Functional Programming would be better practice for it. I feel like it would be functional due to the guidelines of wanting simple calculations with non-mutable inputs but I’m unsure if OOP is typically used for things like that. Thank you all and I hope this is readable…I am awful at using programming terminology.