The one thing I don't get about all those calculator applications is the existence of the keypad. Like, the users already have the keypad right in front them called keyboard (the names literally share the "key" part). Why would anyone instead choose to use mouse to click those tiny buttons? I feel most calc designers still stuck at the skeuomorphism and never jump out of the box to think about what user really needs.…
And I click on the number digits.
Why?
1. Usually I only click on a few buttons, for example I paste some number, then press / then 2, and then typically ENTER key on the numpad (because I can just press it with the thumb of the hand still holding the mouse). Why should I move my hand from the mouse to the keyboard in order to just press two keys? And then I would also need to check if Num Lock is enabled.
2. I had a phase trying Emacs and Vim and eventually decided I don't care about being more efficient at text editing. I want to edit the text effortlessly, and I find selecting text with mouse, or pressing arrow keys repeatedly, actually requiring less effort from me. Yes, it takes more time, but it's not a time lost, I'm thinking about some problem, and no part of my brain needs to think what kind of text editing function I should use. Likewise, clicking a few buttons in a calculator takes more time, but it's not a race. If I have to make a lot of calculations, I'm more likely to use Excel, so it's rare that I actually type stuff into the calculator.
3. Sometimes my left hand is simply not available (I'm petting my dog or eating something or maybe holding my laptop), and while I have a numpad, using functions like sine would require my right hand to travel. In similar vein, sometimes instead of Ctrl+clicking on a link to open it in a new tab, I just right-click, and choose a context option. It does annoy me slightly, but sometimes not enough to start using my left hand.