When the interviewer is wrong?

Nothing to gain by proving an interviewer wrong. State your understanding if they disagree, and correct you do exactly what you did.

Definitely went about it the right way - nothing to be gained from arguing with him. The only other thing maybe you could add is "oh, I thought it was X because I was thinking x y and z but now that you mention T I see ..." and maybe if you're actually right hell realize he was wrong.

The interviewer is NEVER wrong. Sounds like Samesamely forgot the first rule of interviewing... and the second (no stupid questions).

You did the right thing, I don't think any interviewer's ego could cope by being corrected by a candidate.

Had a similar experience. Was asked to do a mental math problem, gave my answer, and the interviewer said not quite (this was over the phone so maybe they didn't hear me). I checked afterwards on a calculator and saw I was right, but ce la vie.

You handled it the right way in 99% of cases, but I will say that I've seen someone give out purposefully wrong information as an interviewer and then dinged the candidates if they didn't correct it... Wanted to see if they had the confidence/courage to speak up. I thought about it afterwards and I actually really admire this strategy and wish more people would promote this sort of logic. FWIW, only two people actually spoke up out of about 15 interviewees. Not sure if that says more about our candidate selection or the state of the population in general, but thought it was interesting.

I think you did the right think. If it were me, I think the best way to go about this would be with a polished response. Next time you might try: "In school, I was taught that the answer was this X because of y, and z. For my knowledge could you explain why that's not the case?"

That moves the disagreement from being personal and, me vs you in nature to a fact-based conversation.

To echo the previous sentiments, the interviewer is always right. They possibly could be trying to test you and how confident you are, but stubborn is not necessary a quality than people are looking for

Short their stock (or buy a put spread, you get the idea) if they're putting incompetents in charge of interviewing.

I had an interview with EY TAS and the guy asked me how to calculate the terminal value on a DCF, granted the perpetual growth rate is more academical, he butted in right after I said perpetuity method (I was going to say AND exit multiple method right after), and he was all cocky like 'NO, you can't do that'. I said upfront I know that its more theoretical, and the other interviewer jumped in and told him that is also a method. Left me with a bad taste in my mouth for EY after that.

(I think that's the two methods, not looked at that stuff in a while)

Dug up my old account just to respond to this thread. The situation you've described is actually a great opportunity for you to be able to evaluate your interviewer.

I'd state what I thought to be correct and why. No way am I working with folks who are both dicks and ignorant (a combination that predicts failure and misery), and you shouldn't want to work with people like that either. [On the other hand, maybe I'd be politely proven incorrect for a reason I hadn't thought of, and that's great too.]

There are a lot of folks in this industry who are bad at their jobs and who screw their underlings over - the interview goes both ways - use the brief interviewing opportunity to suss out the folks on the other side, so you don't become one of the many horror stories we see on here all the time.

You might want to make sure whether that interviewer was testing your honesty. Also, in any case, you don't have to fight, instead just use the technique saying from my perspective blah blah blah.

Wait to see if you get the job abs I'd you don't send them an email thanking them for their consideration and add a Ps explaining how he was wrong