If you are talking about doing the exam at a testing centre, it depends on the centre whether they issue scratch paper or another means of taking notes -- at least that's what I read somewhere on information supplied by PMI. It may have changed since. In my case, in January 2023, candidates were issued a small whiteboard and a couple of fine-tipped whiteboard markers each, in order to make notes. I recall hardly having to write anything on my whiteboard.
There is a calculator built into the exam software (created by Pearson VUE), which can be called up by a mouse click or keyboard shortcut. At the beginning of the exam, there is a lengthy on-screen tutorial about how to use the software, including all the shortcuts. One of the only advantages -- in my opinion -- of paying for a PMI Study Hall subscription, is that you get access through it to the Pearson VUE platform and get to do the intro tutorial and a small set of test questions as many times as you like, and generally get a feel for that particular interface. But without having seen the intro prior to the exam, you're not at any real competitive advantage. As I remember it, I didn't ever need to open the calculator during the exam -- and I'm no mental arithmetic champion!