[antimirov]

I'm almost 34 and when I watch Calculus One videos on coursera, I sometimes get stuck when the guy easily expands (a + b)² or folds it back. We used to to this at math class at school and then probably in university, but I haven't been doing anything like this since then (talking about importance of math for programmers!).

[brewdad]

Very much this. My son is taking his first course in HS Algebra. Fortunately, he generally gets it, but every now and then asks me for help in understanding a concept since his textbook is awful. I've found myself having to Google topics that I know I mastered decades ago. It does come back, but sometimes it takes a bit of thinking.