Solution of problems in Postage Stamp Arithmetic project requires some familiarity with number theory. In particular, here are a few things that might come in handy. Basic divisibility properties; for example, . Greatest common divisors and the Euclidean Algorithm. Knowing that if g is the greatest common divisor of a and b then there exist integers s and t such that . The algorithm for determining g, s, and t is the Extended Euclidean Algorithm.
See the Resources section for ways to learn about these topics.
Students who have only an intuitive understanding of these topics could still work on this project and develop a more formal understanding while they work.