I used to be moderately good at math, then I started using calculators until they rotted my brain. So yeah, I'm often using the calculator on my PC. I also have one of those calculator watches that I use still...since high school, actually. Notepad is another program I often use.
As for smartphone/cellphone, I use it only for what it was originally invented for, as in making calls, so I don't use any of the apps it has. My mother on the other hand...
As for how I would feel without them, the same I guess. Maybe it'll be more of a blessing than anything. Society nowadays has become excessively addicted with technology, so maybe a day or two without it would prove beneficial. Boy will people loose it once we're struck by a solar flare one of these days. Chances are none of us will be alive, but still...