Patterns for a set of Napiers Bones and for a denominate number slide rule are provided, with instructions on how to use each of the calculating instruments. (DT)

An unusual algorithm for approximating square roots is presented and investigated using techniques common in algebra. The material is presented as a tool to interest high school students in the logic behind mathematics. (MP)

Interesting mathematical questions that require computations involving fractions, percentages, and decimals are presented. The material is designed for students in the middle school grades, but many of the ideas could be used with higher or lower level pupils. (MP)

The trick focuses on a theorem that the sum of the digits of the difference between any natural number and the sum of its digits is divisible by nine. Two conditions of using the trick are noted. The reason that the theorem works is established through a proof. (MP)

A subtraction algorithm that does not involve borrowing is presented and called the residue method. It has been taught in junior and senior high school classes and preservice and inservice classes for teachers. The method has helped in classes where arithmetic in other bases is presented. (MP)