Answer to yesterday's was 60. Yet another awesome explanation from @Chase Chan! Challenge results: @Neno N advances to the Quarterfinals (it appears Ria did not know today was the day, maybe). @Arham Aftab advanced to the Quarterfinals (nice job to Mamady)! One small update to how we'll do the challenge, for tomorrow: You must COMPLETE the problem set for it to count. I realize this was a small area of ambiguity in the rules, so I want to make that clear. This is so I can confirm the accuracy and ensure the problems were done. For example, if you start a problem set of 60 problems, you must finish it for it to count (and it must have 75%+ accuracy). I'm glad that this challenge actually rewards skill, to an extent, so nice job boosting your scores in the process. Tomorrow is the day: @Jason Parton v @Mehanth Prabhu @Divit N v @Shiny Av