Water-powered calculator

While most calculators these days are dual-powered (that is, they rely on either the batteries within or on natural sunlight), who would have thought of a water-powered calculator? Well here you have one in the flesh, where electrolytes within water will enable you to ensure that your tax returns are all properly balanced. While this is a rather interesting device to own (at $8.99 a pop it is worth checking out if you have the loose change to spare), one does wonder whether you would use a calculator anywhere else without light. Perhaps a water-powered wireless mouse would be a much better idea.