I've solved 273 as of now (https://projecteuler.net/profile/NabiNaga.png). It took me a little less than 2 years to get to 250 problems, but I was spending quite a bit of time on them haha. I've learned an incredible amount of math and algorithm skills from PE. There have been lots of really challenging ones, but one that stands out is 494. That was the first "really hard" one I solved, and my first time to be in the first 50 solvers.

That is quite an achievement. Can you comment on your background ? type of education, work.

I was finishing up the second year of a computer engineering degree when I discovered Project Euler, and after a few months of solving the problems I realized I wanted to study math instead, so I switched my major to applied math. Honestly I learned more from solving PE problems than school. Now I'm working in industry on AI.

That's encouraging to hear. I'm 30 problems in so far since starting ~1.5 months ago. I starting working through the PE problems to develop my python and general programming skills since I have been primarily using R as a data scientist. I'm glad someone else has found it useful for this field.

My routine was to solve the problem, then spend time reading through the solutions in the forum to see how I could optimize my code. Many times this meant completely rewriting my solution. For a lot of problems I spent more time making my code run as fast as possible than I did solving the problem in the first place. Doing this was critical for learning algorithms and techniques that I needed to solve future problems.

164 here. I did it on and off for many many years. Personally I don't think there is much value in grinding these. It's rather a fun pastime every now and then.

That said, I believe the 100-150 easiest (i.e. solved by the most people) problems are all OK. Many of them take one hour or less. I think, it never took more than a weekend for one.

Many of the ~2006 problems can be brute forced nowadays with a low level language, which makes them quite a bit easier.

In grad school (for math) I used to procrastinate by doing Project Euler problems. I've got that bad habit under control since then (for example, logging in just now, the site told me I haven't done a problem in 56 days!), and am currently at 322 (https://projecteuler.net/profile/oantolin.png).

Don't get sucked in!

I've solved 249 of them. I don't remember when I joined, but it must have been about 10 years ago. Solving PE problems was a great way to unwind in grad school (studying math) and learn some cool math in the process. There was a period where I was knocking them out pretty frequently, but I've only had the time to solve 4 problems in the past year.