Before smartphones could do it with apps.
Here's the thing: I lost my pocket calculator in January and I really miss it. I'd had it for over 20 years and it was (for it's day) a really good one: scientific, did hexadecimal (one of my requirements for work use) and solar-powered.
Yes; I've got a scientific calculator on my smartphone (although the basic one that came with the phone doesn't do binary/hexadecimal), and yes; over the last couple of years I've tended to favour it over my old pocket calculator. However the pocket calculator still has its advantages, such as the keys being bigger and they give you a nice physical response when you press them - I often find myself making mistakes when I'm doing a lot of calculations on my phone because I miss that "feedback".
And for anyone who thinks I'm a luddite for preferring my pocket calculator, just remember that Sir Clive Sinclair still carries one of these bad boys around with him everywhere he goes: