It's funny that his expected answer was "Google it". In most cases when people answer with that (it could be the answer for any tech interview question...) you get encouraged to actually do the problem, so it's a time waster. For the interviewer it gives them no signal outside of you having the ability and awareness of the existence of search engines, although there could be some vague behavioral signal that shows you have a stronger urge to find existing solutions rather than waste time creating your own. This is a really toxic interview because you're basically expected to read the interviewer's mind. I've had a couple of these with peak Silicon Valley companies. At pre-IPO Zynga I was asked by a GM "what the most important number in game design is", at River Studios (Mike Rothenberg's company...) the entire interview was basically this style of question.