I still have the same scientific calculator I used in high school. All the markings on the keys have long since worn off, but my muscle memory is so strong that I am speedy and accurate in typing.

For isolated, unimportant calculations, I’ll use my phone or the calculator on my computer, but for anything more than that, I relish the chance to use my proper calculator. I think using it puts me in a particular frame of mind where I’m more focussed too, like my brain is going “okay, let’s buckle up, it’s maths time, let’s have no silly mistakes, keep on task”