bones which became known as Genaille–Lucas rulers. By representing the carry graphically, the results of simple multiplication problems can be read directly, with no intermediate mental calculations. The following example calculates . See also Genaille–Lucas rulers Pascal's calculator Slide rule References External links Wolfram Demonstration implementation of Napier bones in various number systems at cut-the-knot Napier and other bones and many calculators Mechanical calculators Scottish inventions Multiplication