Yes interesting. I also had no trouble with question #3, it must reveal something about how various people do addition in their heads. For met it was a simple as (4x1000) + (40+30+20+10). Missed the first one though. Questions #4 and #5 were easy since I had been primed by the first to look for clever twists. It would have probably been best to attempt to answer all of them before looking at any solutions. I missed #2 because I was visualizing overtaking the person in front of me, neglecting to consider that I was therefore last.