The department has a self-advising handbook for undergraduate math majors and minors. You'll find most of the information you need in it. Here I put together a quick summary of courses as well as how to get a research experience as an undergraduate.
The Mathematics Department at Brooklyn College offers a BA in Mathematics, a BS in mathematics, a BS in Actuarial Mathematics, and a BS in Financial Mathematics.
It helps to begin college having done Precalculus, so you can start with Calculus I in your first semester (typically in the Fall). Many students have already taken Calculus in High School and if you have done AP Calculus and passed the exam with a suitable core you don't need to take Calculus I. However, it can be tough to take Calculus II in your first semester of college having done Calculus I at some point before. That is why I recommend beginning with Calculus I. If you have taken AP Calculus BC and obtained a suitable score in the exam, then you do not need to take Calculus I or II.
The difference between a BA in Mathematics and a BS is just more math courses. Let's begin with the following flow-chart from page 6 of the advising handbook.
So assuming you begin with Math 1201 (Calculus I) and the computer science course (CISC 1115) in the Fall, you can take Math 1206 (Calculus II) and Math 2101 (Linear Algebra) in the Spring.
In the Fall of your sophomore year you can take Math 2001 (Transition to Higher Math) and Math 2201 (Calculus III).
In your junior year, you can take Math 3101 (Abstract Algebra) and Math 4201 (Advanced Calculus).
With these required courses out of the way, you must choose 2 courses from the following list:
4101: Linear Algebra 2
4106: Abstract Algebra 2 (prereq 2206)
4206: Advanced Calculus 2
4211: Partial Diff Eqns
4216: Complex Analysis)
4302: Geometry
4306: Topology
4501: Prob and Stats II (prereq 3501)
4506: Time Series
4511: Probability (prereq 3501)
4701: Numerical Analysis (prereq 2206)
Now here's the thing - Part 2 courses are best avoided. It is better to get a well-rounded education by taking a variety of math courses. Part 1 courses are well regulated, but the syllabus of the Part 2 courses is vague. Part 2 courses don't fill up and are canceled or run as partial courses/independent study courses.
I would recommend taking Math 2206 (Differential Equations) because it is a very useful course filled with applications. It is only when you take Differential Equations that you understand why you studied certain topics in Calculus II. After that you can Math 4701 (Numerical Analysis) which is another fantastic and useful course. Then take Math 4302 (Geometry).
With these courses you will have 15 credits. You'll need to take one more course to bring the total number of credits in advanced math courses to 18. For the BS degree you must take a total of 24 credits in advanced math courses. So that is a total of 3 more math courses. You are free to take any math elective offered in the department to meet the additional requirement.
I highly recommend taking Math 3111 (graph Theory and Applications). This is a course for the times filled with real-world applications,
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Freshmen
Fall: Math 1201 (Cal I), CISC 1115 Spring: Math 1206 (Cal II), Math 2101 (Linear Algebra)
Sophomore
Fall: Math 2001 (Transitions) Math 2201 (Cal III) Spring: Math 2206 (Diff Eqns)
Junior Fall or Spring
Math 3101 (Abstract Algebra), Math 3501 (Prob & Stats I), Math 3111 (Graph Theory)
Senior Fall or Spring
Math 4701 (Numerical Analysis), Math 4302 (Geometry),
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For the BS degree take two of Math 3106 (Number Theory), Math 3402 (Math Modeling). Math 4306 (Topology), Math 4211 (Partial Diff Eqns), Math 4216 (Complex Analysis. This gives you a well-rounded mathematics major.
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Most importantly leave time in your schedule to take Math 5001 in the spring of your junior year or fall of your senior year. Math 5001 is an independent study course. You can work with a professor on an REU project in the spring and if you enjoy research you can continue in the fall by taking Math 5002. This way before you graduate you can list an undergraduate research project, talk, poster presentation, and even possibly a paper on your resume.
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Now if you are interested in the Applied Math Track, then you are required to take Math 2206 (Diff Eqns) and Math 4701 (Numerical Analysis). But even as a theoretical math major you should take these two courses as explained previously. The only other required course for the Applied Math Track is Math 3202 (Math Modeling). The other two courses you should take are again Math 5001 and 5002.
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The Computational Math Track has three more CISC courses that are required (CISC 3115, 3130, 3220).
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By taking Math 5001 and 5002 you can fill requirements easily and have an undergraduate research project or an independent study project to list on your resume.
Fill in the rest of your courses with general education requirements and courses you enjoy. Last, but not least, Math 2011 (History of Mathematics) is a fantastic course to take to full fil your writing requirements. All math majors on any track should take this course.