Answer to last teaser: The man is a dwarf. Everyday he rides the elevator to the bottom floor, but on his way up he can't reach the elevator button to the penthouse floor. So instead, he rides to the highest level he can reach, then walks the remaining way up the stairs. On rainy days, he uses his umbrella to press the button.
Great stuff you guys! I saw a lot of right answers in the comments. That tells me my followers aren't just a bunch of dummies =). With no riddle challenges, let's go on to today's riddle! This next one is a classic stress test that is commonly used in interviews. It can also be used to gauge intuition, creativity, problem solving, attention to detail, calculation, etc etc... There is no trick; the point is not to get the right answer, but instead to derive a detailed method that would allow you to arrive at an approximate number. I hope everyone gives it a shot because I'd like to see some deep thinking here! Remember, no wrong answers!
How many golf balls would fit inside a school bus?