It's always amusing how different institutions number their classes. At the Claremont Colleges, I took a class Math 103 - Fundamentals of Mathematics which was an upper division course geared towards preparing students for analysis, abstract algebra, etc. Because I started college having completed my math coursework through linear algebra and differential equations, this was the lowest-numbered math course on my transcript from Claremont and when I started grad school for a teaching credential a couple decades later, the program director thought that it was a remedial math course.

Recent Pomona College alum here checking in to say that the course numbering system has not changed (though Math 103 is now Intro to Combinatorics), and anecdotally it's still a point of confusion for those who go on to the grad schools the Colleges feed into.

I've never before paid course numbers too much mind, but it does surprise me there's not yet some widespread standard of to help graduate admissions officers, graduate advisors, and grad students themselves when determining prerequisite eligibilty.

Yeah, I was looking for the class to see what the number was and it doesn't appear to exist anymore. I remember being amused that at Mudd, Calculus as Math 1a/b back in my day. It appears to have been renumbered a bit higher since then and now they only offer one semester of calculus (back in the 80s it was radical that Mudd did the Calculus sequence in two rather than three semesters, although I noticed that our local high school offers a third-year high school calculus class covering multivariable calculus).

It's surprising to me - 300+ level courses were part of my undergrad required coursework - of course I wasn't studying at Stanford. Are course numbers standardized across academia or unique to an institution?

Course numbers are not standardized, although there are common numbering schemes. There are some uncommon ones such as MIT's, which uses a number and a dot instead of a subject name. And I've never known what institution the typical "CS 101" numbering scheme applies to.

Afaik they're unique—and not monotonously increasing in difficulty either. Here's Stanford's numbering system for reference: https://cs.stanford.edu/academics/courses

This class is available on SCPD, so it's open to (almost) anyone willing to pay >$5k.