It was Nate Hagens (The Great simplification podcast) who said this when he worked at Lehman Brothers about confidence. Don't worry, he learned quickly that he was the bad guy and changed his ways completely.

Anyway, when all the new recruits came in they gave them a pop quiz. It starts off simply "What is a derivative?" "How to bonds work?", and with everyone being young an confident they all answer enthusiastically. Eventually they drop in a question that is really difficult and oddball that nobody would know, naturally everyone starts trying to formulate and answer only to have the teacher stop them. Teacher just says, "Don't try to fake it, that helps no one. What you say is. I don't know, I will find out, and I will get back to you."

You don't have to have an answer to everything.