[jonas21]

You're treating this as a binary thing -- either you know something or you don't -- like it's rote memorization of facts.

But that's not how problem solving works. You need work your way from what you do know to get to an answer for what you don't. It's not guessing -- it's taking the background knowledge you do have and applying it to the problem at hand (and every engineer should have some background knowledge, even if it's just basic arithmetic).

That's what these kinds of questions are testing. Someone who immediately gives up is probably not going to be resilient in the face of new challenges.

[notarget137]

Problem solving isn't a binary thing either. You are not just capable of solving problems on the spot or not. Different people have different approaches on the same problem under different conditions. Interview is not one of the things that really shows your problem solving skills rather your skills to solve arbitrary dumb problems right there on the spot.

I've quit several interviews because of these particular questions since they are simply wasting my time and not testing my "skills".