There are many online calculators that will work just fine for many applications. Make sure you know how to use a physical graphing calculator, because you won't be able to use phones or computers. There is a free app called Desmos that will work for many applications. There is also a TI Calculator emulator called Wabbit. It takes a little bit of fiddling to get running, but it works exactly like a TI calculator once you do. Here is a youtube video that walks through getting Wabbit going. You can also just do an internet search like "linear regression calculator" or "correlation coefficient calculator" and usually find something that will work pretty easily for specific applications.