Contrast to other math degrees

The obvious alternatives to an ACMS degree are the BS degrees in mathematics, computer science, and computer engineering. The following few paragraphs are intended to help you make the choice that is right for you.
Note first of all the term "mathematical sciences" is a misnomer. According to the Oxford English Dictionary, In modern use, ("Science" is ) often treated as synonymous with "Natural and Physical Science", and thus restricted to those branches of study that relate to the phenomena of the material universe and their laws, sometimes with implied exclusion of pure mathematics. This is now the dominant sense in ordinary use.

Applied mathematics, computer science and engineering, and statistics are not sciences but rather engineering disciplines, while pure mathematics is in a category by itself. The goal of engineering disciplines is to provide tools - for computing the lift of an airplane wing, for encrypting information transmitted over the Internet, for providing ubiquitous high speed wireless Internet access, for summarizing and displaying click data from an E-Commerce site. The primary criterion for evaluating the work of an engineer is utilitarian: is the tool useful? The primary criterion for evaluating the work of a mathematician is aesthetic: are the definitions, theorems, proofs beautiful and do they contribute to internal structure of mathematical knowledge? This by no means implies that mathematics is not useful; nothing could be further from the truth. Highly abstract areas of mathematics seemingly far removed from the "real world" (like number theory) have turned out to be fundamental to the solution of engineering problems (like encrypting information). It is just that usefulness is not, and should not be, the criterion.
Beauty is not only evident in mathematical research. You can encounter and enjoy it even in undergraduate courses like Abstract Algebra, where the definitions, the theorems, and the proofs have been polished to a high gloss by generations of mathematicians. For more information on the various degrees offered by the Mathematics Department, follow the link to degree programs in "Undergraduate Program in Mathematics"
(http://www.math.washington.edu/Undergrad).

If you are the kind of person who enjoys collaborating with others in solving concrete problems, then you might choose the ACMS major or one of the CSE majors. An important difference is that the ACMS major has a much broader mathematics content than the CSE degrees. You will have to learn what constitutes a proof, as well as some basic techniques for proving theorems. Definitions and methods will be primarily expressed in the language of mathematics, rather than in the form of data structures and algorithms.

A fundamental concept at the core of the ACMS program is modeling - casting a real world problem in a way that makes it amenable to mathematical, statistical, or computational analysis. Modeling is a creative activity and often a crucial step in understanding problems. A prototypical example of modeling is kinetic gas theory. Kinetic gas theory models the atoms or molecules in a gas as elastic balls moving with a certain distribution of speeds. From this simple model many of the properties of gases, like the connection between pressure and temperature, can be derived using mathematical arguments. Somewhat simplified, models come in two varieties, discrete - thinking of a DNA molecule as a string over a four letter alphabet , or continuous - thinking of the pressure over an airplane wing as a real-valued function on a two-dimensional surface. Many models, like kinetic gas theory or Mendel's famous model of inheritance, have a statistical component. Continuous modeling, while central to many applications, is not part of the CSE undergraduate curriculum, and statistical modeling is only a small component.