Numbered rods which can be used to perform Multiplication. This process is also called Rabdology.
See also Genaille Rods
References
Gardner, M. ``Napier's Bones.'' Ch. 7 in Knotted Doughnuts and Other Mathematical Entertainments.
New York: W. H. Freeman, 1986.
Pappas, T. ``Napier's Bones.'' The Joy of Mathematics. San Carlos, CA: Wide World Publ./Tetra, pp. 64-65, 1989.