Project Euler Forum

Most of the first 50 problems only require high school level mathematics (e.g. prime numbers, algebra, geometry, trigonometry) or pre-university level mathematics (e.g. series summation, calculus, combinatorics, vectors) to solve. However, I would expect many of the later problems to only be solvable with undergraduate-level or graduate-level mathematics.

How does one identify the level of mathematics required to solve specific problems? Are the difficulty levels, tags and terms used good indicators?

I don't think there is an objective "level of mathematics" (and in the education systems I'm familiar with, people go straight from high school to university so your "pre-university level" doesn't even make sense as a concept). I know that I studied some things in school which my mother studied at university, and didn't study some things ever that she studied at school. I believe that in some universities combinatorics isn't on the undergraduate syllabus, so would be a graduate-level subject.

I would say PE is somewhat similar to competitive math, and although some problems can be quite challenging, they don't require any fancy graduate-level mathematics and generally are accessible to undergraduates and advanced high school students.

I would argue there are a decent number of later problems that require topics that are not commonly covered in an undergrad math curriculum, although they're not strictly harder than anything covered in undergrad - as the most non-spoilery example I can think of, there are a couple of problems that would be very difficult to solve without knowledge of the Sprague-Grundy theorem.