And now, a little backstory.

I grew up in a small village, and I started studying mathematics with my teacher, Konstantinos. He did not just teach me how to solve exercises; he taught me how to think mathematically: to ask why a method works, to look for the idea behind a problem, to stay with a question until it made sense. Mathematics competitions came up later, during school. That is where I found the meaning behind creative thinking, and where I fell in love with problem solving: the moment a problem that looked impossible suddenly opens up.

A little later, astronomy and astrophysics competitions came along and followed the same path, but in a different way. Mathematics had taught me to think on paper; astronomy taught me to think by looking up at the sky and observing the world around me. The questions were no longer only why does this work, but also what is that light, how far away is it, and how do we know. It was the same love for problem solving, pointed at the universe.

Beyond his lessons, though, resources were thin. There was no prep school down the road, and no teacher who specialised in competition problems. If I wanted to work on a hard problem, I had books, photocopied notes and whatever I could find online.

The problems themselves were never the frustrating part. The searching was. A past paper in one PDF, its solution in another, sometimes only the statement and no solution at all. The idea I needed was usually in some book I had already read, but I could not remember which one, or which chapter. Many evenings went into looking for things rather than thinking about them. And when I finally found a solution, it was all or nothing: either I saw the whole answer, or I stayed stuck.

It was also lonely in a quieter way. There was no one around me who shared these interests, no friend to argue with about a geometry problem. Between lessons, I was mostly on my own, figuring out what to study, in what order, and whether I was getting anywhere. There were days I struggled, and days nothing seemed to work. But I didn’t give up. I kept pushing, a bit like an anime character training alone before the next big fight, or a Pokémon that wants to evolve: every problem I couldn’t solve was experience points, and every one I finally cracked made me a little stronger. That is how I reached many of the goals I set for myself. Not because the path was easy, but because I kept going when it wasn’t.

What I needed was simple. One place with the problems, organised by competition, year and topic. A hint before the full solution, so that I could still finish the problem myself. The piece of theory a problem relied on, right next to it. And someone to say: these three problems today, at your level, and this one again in a few days, because you didn’t get it the first time.

Years later, I built that tool, twice.

Mathematical Olympiads collects problems from the Hellenic Mathematical Society’s competitions, Thales, Euclid and Archimedes, with their official solutions. Astronomy & Astrophysics does the same for the Panhellenic Astronomy and Astrophysics Competition, the route to the International Olympiad on Astronomy and Astrophysics.

A few principles came straight from that village:

• Free, and no account. Nothing should stand between a student and a problem.
• Honest. An official solution is marked as official. A solution written for the archive says so.
• A hint before the answer. Being stuck is part of learning, as long as you are not stuck alone.
• A little every day. Three problems, at your level, is a habit you can keep.

Building them has been a full-circle moment. Every feature answers a question my younger self had: where do I find this, is there a hint, what should I do today. In a way, I built them for him, and for the way of thinking Konstantinos first showed me.

Somewhere, in a village like mine, a student is searching through notes right now, maybe without anyone nearby who shares their curiosity. I hope these tools save them a few evenings, and remind them they are not as alone in this as it feels.