Bruce Sherwood, the author of Matter and Interactions, had a question for me when I saw him at the American Association of Physics Teachers conference not long ago: "What calculator do you use?" If this seems odd, well, it was a conference of physics teachers. I responded with something along the lines of "I don't actually use a calculator." Of course, Bruce probably knew I'd say that. He absolutely agrees with me. I don't remember the last time I use a traditional calculator.