Yes, I have a few, and I do use them from time to time. I keep one in my daily backpack along with an abacus; mostly just to surprise people when I don't pull

Yes, I have a few, and I do use them from time to time. I keep one in my daily backpack along with an abacus; mostly just to surprise people when I don't pull out my phone to some more complex calculations that I can't easily do in my head.