The Slide Rule Watch. I’m sorry, but to do this properly they really ought to have made it steam driven too. But hey, it’s a start. $250.00.
This watch from Torgoen will allow you to step back in time a little bit. Featuring a circular slide rule that can solve time, distance and speed equations, it can also perform a wide variety of calculations. These include currency conversions, multiplication and division and any conversion of a linear nature such as ounces to grams, kilograms to pounds, miles to kilometers, etc.