Interviewer: "Okay, for this next question, I'd like to see how you think. Tell me, how many cars are there in the world?"
Me, picking up my phone: "Hey Google, how many cars are there in the world?"
Interviewer: "Um, perhaps you didn't understand the purpose of the question. I don't really want the answer... I'm looking to see your thought process."
Me: "Oh, I understand. But my thought process is that before I spend a lot of time doing a lot of math based on a lot of assumptions, I should check the world's largest source of instant information to see if it has a credible answer readily available. Because if it did, that would get me the answer you needed while saving us both a lot of time, right?"
Me: "Thinking about the best way to solve the problem is the first step in my thought process. Checking to see if somebody else has already solved the problem you're looking to solve is my second step. And after I've done both of those things, if I still don't have a good answer, then I get to work."
Interviewer: "That's great! You're hired!"
Okay, fine, this story didn't actually happen.
But only because an interviewer has never asked me that particular question before.
P.S. As it happens, Google actually yields an answer to that particular question, and the source appears to be quite credible. See? It works.