Addis: Could I have my bill, please?
Ingelbert: Certainly, sir.
Addis: I'm afraid there's been a mistake.
Ingelbert: I'm sorry, sir. What seems to be the trouble?
Addis: I believe you have charged me twice for the same thing. Look, the figure of 6. 5 dollar appears here, then again here.
Ingelbert: I'll just go and check it for you, sir.
Addis finds a mistake on the bill, and Ingelbert will check it.