sqrt( (1000)(1001)(1002)(1003) +1 )
Like high-school math problems, they are manufactured puzzles (i.e. with a neat solution), which narrows the search space and tells you if you are on the right track. But unlike those, these have 2-3 tricks, so you get no feedback after the first step. It seems a bit like NP-complexity: hard to find the method; easy to check.
I'm sure there are many math olympians here on HN (and winners), who would find these unchallenging. Speaking for myself, I can do most in my head, and most of the remainder on paper - when I need their answer is when I learn the most.
A maybe-criticism: the answers are very clear, but they don't say why those steps were chosen. To me, the channel is more like a slightly-cleverer peer, rather than a super-genius master. Sometimes I find a better method, and it becomes a springboard for related ideas. And all that might well be better for learning.