I thought professionals would know the lingo

Client: We need you to design a banner for us using the logo you created.

Me: Sure, okay. What are the dimensions?

Client: Well… here’s a picture of the room to give you an idea of how big it should be.

Me: Okay, but I need exact numbers.

Client: (frustrated) How do you expect me to know? I’m not in the room to measure it!

Me: I’m afraid I would only be wasting time without measurements.

Client: Fine, okay. Hold on, my co-worker just texted me; yeah, he said that it should be four laptop sizes wide.

Me: …Okay, so is this banner going to be digital now? Like, on a screen?

Client: I don’t see what’s so difficult about this. You’re supposed the be the expert.