The Casio fx-260 Solar scientific calculator is a handy little device. I recently found one on ebay that’s even handier; it has a magnetic strip on its case so you can stick it on a magnetic surface. The ebay description said it was a “30 mil magnet”; not knowing what that was, I had to look it up. Discountmagnets.com‘s page provided a good description of magnetic sheeting and included some prices. Other companies’ websites from the Google search may also be helpful.