There are a lot of ways to complete a major in mathematics over the course of your college career. Below are some sample pathways. You should construct your own path in consultation with a math professor, taking into account your prior math preparation, interests, and other commitments. Here are a few general principles to keep in mind:
 Aim to complete the core courses  MATH 111, 121, 211, and Linear Algebra (MATH 271 or 272)  by the end of your sophomore year. It would be good to fit in at least one other math course by that time, also.
 There are usually more math electives available in the Spring than in the Fall, so plan accordingly.
 Aim to take at least one of MATH 350 or 355 by the end of your junior year.
 Most math majors should take at least one 200level math elective before attempting MATH 350 or 355. Talk to a math professor for advice about what you should do; we can make a good recommendation based on your experiences in MATH 211 and 271/272. Sometimes, if MATH 211 doesn’t go as well as you would like, it might even be advisable to take MATH 220 before taking 271/272; again, check with a math professor for advice on this.
It doesn't matter which of MATH 350 or 355 you take first. But in whatever semester you take your first of those two courses, try to make sure the rest of your course schedule isn't overly demanding.
Here are some possible pathways; there are, of course, MANY other possible combinations.
An Example Starting from MATH 111  

Year 1: Fall: MATH 111  Spring: MATH 121, outside elective 
Year 2: Fall: MATH 211, outside elective  Spring: MATH 272, MATH 220/250/260/280 
Year 3: Fall: MATH 355  Spring: Math elective 
Year 4: Fall: Math elective  Spring: MATH 350 
An Example Starting from MATH 121  

Year 1: Fall: MATH 121  Spring: MATH 211, outside elective 
Year 2: Fall: outside elective  Spring: MATH 272, MATH 220/250/260/280 
Year 3: Fall: MATH 350  Spring: Math elective 
Year 4: Fall: MATH 355  Spring: Math elective 
An Example Starting from MATH 121, with Junior Year Abroad  

If you spend your junior year at an institution where you can't realistically take math, you will have to double up a bit, of course:  
Year 1: Fall: MATH 121  Spring: MATH 211, outside elective 
Year 2: Fall: MATH 271, Math elective  Spring: MATH 350 
Year 3: Fall:  Spring: 
Year 4: Fall: MATH 355, outside elective  Spring: 2 Math electives 
An Example with a Late Start to the Major  

If you start in MATH 105, or you delay MATH 111 until your second semester, it may still be possible to complete a math major, although some of your later semesters will be challenging:  
Year 1: Fall:  Spring: MATH 111 
Year 2: Fall: MATH 121  Spring: MATH 211, MATH 220 
Year 3: Fall: MATH 271, outside elective  Spring: MATH 355 
Year 4: Fall: MATH 350, outside elective  Spring: 2 Math electives 
Honors in Mathematics  

If you want to do honors in mathematics, aim to complete both MATH 350 and 355 by the end of your junior year. It would be good to fit in another 300 or 400level elective in that time, too.
If you are starting from MATH 121 or higher, you have a lot of possibilities, such as the following. 

Year 1: Fall: MATH 121  Spring: MATH 211 
Year 2: Fall: MATH 271, outside elective  Spring: MATH 350 
Year 3: Fall: MATH 345, outside elective  Spring: MATH 355, Math elective 
Year 4: Fall: Thesis  Spring: MATH 450/455, Thesis 
If you are starting from MATH 111, you can still do honors, provided you can get through a challenging semester or two, such as in the following  

Year 1: Fall: MATH 111  Spring: MATH 121, outside elective 
Year 2: Fall: MATH 211, MATH 271  Spring: MATH 250/260/280 
Year 3: Fall: MATH 355, outside elective  Spring: MATH 350 
Year 4: Fall: MATH 345, Thesis  Spring: MATH 450/455, Thesis 
If you spend a semester abroad, aim to spend it at a place where you can take some math courses that can count as electives or in place of MATH 350 or MATH 355. If that's not possible, honors is usually still feasible, with appropriate planning. For example:  
Year 1: Fall: MATH 121  Spring: MATH 211, outside elective 
Year 2: Fall: MATH 271, Math elective  Spring: MATH 355 
Year 3: Fall: MATH 345, MATH 350  Spring: 
Year 4: Fall: outside elective, Thesis  Spring: MATH 450/455, Thesis 
Preparing for Graduate Study in Mathematics  

If you want to go on to pursue a doctoral degree in mathematics, you should plan to accelerate things a bit more, to complete more highlevel courses before your senior year, as well as to allow time for some graduate courses at UMass. For example:  
Year 1: Fall: MATH 121  Spring: MATH 211, outside elective 
Year 2: Fall: MATH 271, Math elective  Spring: MATH 350, outside elective 
Year 3: Fall: MATH 345, Math 355  Spring: MATH 450/455 
Year 4: Fall: Thesis, UMass Math 611  Spring: Thesis, UMass Math 612 
Advanced Students  

If you start from MATH 211 or higher and want to take a lot of math, you will not run out of challenging course options, thanks to UMass. For example:  
Year 1: Fall: MATH 211  Spring: MATH 271 or 272, outside elective 
Year 2: Fall: MATH 355, outside elective  Spring: MATH 350, Math elective 
Year 3: Fall: MATH 345, UMass Math 623  Spring: UMass Math 624, Math elective 
Year 4: Fall: Thesis, UMass Math 611  Spring: Thesis, UMass Math 612 
Always feel free to contact any of your math faculty for help navigating the math major!