Since the carpets in the elevator are changed daily (each day of the week has their own carpet), before the crowd starts to gather in the elevator that day, take a picture of the carpet. This helps keep track of the days of the week (especially if your camera doesn't have a date function on it). Then for the rest of that day you'll be able to remember what you did say on Tuesday or Friday. It also makes it easier later when you’re back home and trying to assemble all 300 plus pictures into your photo album.