This classroom note includes the following sections: Introduction; The General Case; and Related Formulas.

Simplicity in number naming in a language (e.g. "ten-two" in Chinese is simpler than the irregular "twelve" in English) has been used to explain cross-cultural disparities in children's computational competence. In contrast to previous research focusing only on whether children can provide the correct answers, in this study (N =117 and 92) we…

Illustrated is the use of arithmetic modulo 2 for finding the truth values of logical statements. (MM)

Divisibility tests for digits other than 7 are well known and rely on the base 10 representation of numbers. For example, a natural number is divisible by 4 if the last 2 digits are divisible by 4 because 4 divides 10[sup k] for all k equal to or greater than 2. Divisibility tests for 7, while not nearly as well known, do exist and are also…

Behavioral, neuropsychological, and brain imaging research points to a dedicated system for processing number that is shared across development and across species. This foundational Approximate Number System (ANS) operates over multiple modalities, forming representations of the number of objects, sounds, or events in a scene. This system is…

Presents a system for quick conversion of Chinese cyclical-binary dates to western year dates. (CHK)

The problem of getting a correct result when a fraction is reduced by cancelling a digit which appears in both the numerator and the denominator is extended from the base ten situation to any number base. (DT)