<p>Early in the semester, basic algebra and analysis 1 may have 80-120 students, by the end of it, it's closer to 50-80 (at least back in my day). After that it depends what classes you take. Honours version are much smaller (15-30 in analysis and algebra 2, usually), for majors it depends. I've had as few as 5 in differential geometry and as many as 70-80 in history of math (I think). </p>
<p>I am forgetting core classes that other programs may require (in some form). Probability and statistics, major's version (MATH 323 and 324), can have over 100 student as well (it's common to other programs in science, though most non-math students probably take the 200 versions instead). In those cases it may depend on the semester also , ODEs (325, Honours) is filled (or at least used to be) with engineers in the fall, not so much in winter. Taking 323-324 in winter then fall of the next year is probably less crowded than the standard fall-winter combo.</p>
<p>For prof accessibility and quality, it varies also, but the thing is you have to go to them (that's what's expected at McGill: you have to take the initiative for everything). There are opportunities for undergrad research, all you have to do is inquire. Don't be afraid to talk to your professors about your education/career plan and hopes. Also, go the undergrad society. Hopefully SUMS is not a squalid hellhole filled with drooling asocial nerds. It used to be very welcoming back in the day, now I don't know. It changes from one year to another, I do believe they still publish a "survival guide" for new students every year. So at least that should be helpful. If they have a good exec when you're there, then their advice may be better than most advisors'. If it's a bunch of drooling nerds, just pick up the survival guide and avoid the place...</p>
<p>I'm not familiar with finance so much, but I believe the classes may be large. CS used to be huge back in my day (100+ students per class, except for hardcore abstract 400-500 level classes, it was the fastest growing department at the time), it may not be the case anymore.</p>
<p>GPA: let me put it this way (applies to grad school only, I don't think employers care that much). In your final year, you'll probably apply for FQRNT and NSERC grants/bursaries, whatever they're called. Minimum GPA for FQRNT is 3.3, NSERC is 3.5. You don't get anything if you just have the minimum (you'll still get into grad schools with these grades of course, but with limited choices in terms of schools and funding). Some grad schools (e.g. some SUNY's) will consider math applicants with as low as 2.7 GPA, but if you want some money and decent chances of being accepted in places, try to maintain at least a 3.3 from the beginning (and improve). 3.5 is better, anything 3.7 or above is pretty impressive for math. Good references letters are a must, so choose which profs to write them wisely (they should know you more than just by name and grade in their class, and be active researchers).</p>
<p>WRT recruitment, I have no clue, but if you keep with McGill philosophy, you're the one who should seek out employers, not wait for them to come recruit at McGill (I saw the CS job fairs dwindle with the dot-com bubble...). A McGill degree does carry some weight on a CV (I have classmates who work on Bay street or doing finance in places like Chicago or working at the Bank of Canada).</p>