The reason we're talking 'bout this is because your best friend when solving math is... THE CALCULATOR!!!
So, we're going to talk about some goated calculators!
Honestly, Texas Instruments is my favorite brand of calculators. Why, though?
First, you have the iconic TI-84 Plus, with a CE and Evo version!
Secondly, you have the TI-Nspire series, containing many, with the Nspire CX II CAS being the best (my dream calculator, although I would be impressed with a non-CAS CX II as well).
Obviously, there is more than one brand. I don't know many physical non-TI calculators, but Casio offers very affordable calculators (Casio FX-260 Solar II, Casio HS-8VA etc.) too.
When it comes to online calculators, there's a name above all else... you should know this!
Desmos, first of all, is what online standardized tests offer as a calculator, making it already famous.
Secondly, you can make very cool simulations with it!
Have you made one? If so, you should share it!