Elementary number theory is a standard topic in the mathematical preparation of preservice elementary teachers. To understand elementary number theory, a student must be comfortable with the representation of natural numbers as the product of primes. This paper discusses methods for accomplishing this goal in a mathematics course. It also considers the role of measurement (quotitive) division in justifying divisibility results and demonstrates one way that this connection can be exploited to strengthen student understanding of multiplication and division. The appendix contains three worksheets for students to complete. (ASK)