Haha, back then I wasn't really into database applications and built it just to experience it. That's how I know that 2-back is fairly easy and 3-back isn't, bu

Haha, back then I wasn't really into database applications and built it just to experience it. That's how I know that 2-back is fairly easy and 3-back isn't, but beyond that I can't answer you (yet). I gave my dad a 3-back test, on which he did surprisingly well, and he said, "oh, that's easy, all you have to do is concentrate." Indeed, a big portion of it is attention.