Many of us use a desk calculator regularly. For years I’ve had a calculator on my desk, right next to my computer, for those times I need to do arithmetic quickly.
Nowadays, I just call up the calculator on my computer & use that instead. You can find the MS Windows Calculator under the Start Menu / Accessories. You can even created a shortcut on my desktop to access it quickly.
For those of us that like a more customised calculator, you may like to download one of the freeware versions that are available. My favourite is WP-34S, which is an RPN calculator (like HP’s financial & engineering calculators). It’s a bit of a carryover from my engineering days, but I prefer RPN, where you enter the numbers then perform the function. It makes chain calculations much simpler.