Dear Jim,
A solar calculator is a good tool to have, but old style slide rules never require any batteries, do all major math functions, and provide a visual aid for teaching logarithmic functions. It’s worth having, and learning to use, a couple of those, too. – Michael Z. Williamson – SurvivalBlog’s Editor at Large
Letter From Mike Williamson Re: The Pen is Mightier than the Sword
