Can I offer you some advice? An interview is a negotiation. The rules aren't fixed. If you're asked to do something that won't give a reliable measurement of your ability, say so and offer the interviewer a better option. You'll probably get what you want.
In the scenario you described, I might try something like this: "I think I see what you're trying to measure by asking that question, but it assumes a working style that is foreign to me. So that you can get a better reading of what I can really do, would you mind if we used my laptop, with you looking over my shoulder, as I solved a problem of similar difficulty?"
An interview is a negotiation. If you want to change it, just ask. Most interviewers will be happy to agree to any changes that will help them get a better read on your true abilities.
In the scenario you described, I might try something like this: "I think I see what you're trying to measure by asking that question, but it assumes a working style that is foreign to me. So that you can get a better reading of what I can really do, would you mind if we used my laptop, with you looking over my shoulder, as I solved a problem of similar difficulty?"
An interview is a negotiation. If you want to change it, just ask. Most interviewers will be happy to agree to any changes that will help them get a better read on your true abilities.