An interesting maths question
You have 2 supposedly unbreakable light bulbs and a 100-floor building. Using fewest possible drops, determine how much of an impact this type of light bulb can withstand. (i.e. it can withstand a drop from 17th floor, but breaks from the 18th).
From http://maxnoy.com/interviews.html(and no, I will never be going to a Programming interview, it was just random interneting).