Just because you can doesn’t mean you should 
You mock me! How dare you!

No, it's just that in my typical workflow, whenever I need a quick math answer, I always have a couple of terminals already open, and it's just faster to run a script, than fire up a proper calculator GUI. Plus, if I forget, it'll still be in my command buffer (
~/.bash_history). It's all about being lazy, and getting a reliable answer with the least amount of effort spent.
My second most favourite calculator is a piece of paper. I don't like doing math in my head at all, but doing it on paper is fine for me. It's like doodling on paper when I'm thinking.
Just recently I was thinking about kids having difficulty motivating themselves to remember e.g. multiplication tables or fractional multiplication in your head (like
price × (1 - 0.25) for 25% off). I thought how one wouldn't want to walk around in a store looking at your phone, tapping on it, just to understand the prices around you. Then, I remembered that that's exactly what the kids do nowadays anyway..
