It Keeps Saying Error

(I work in a cell phone store. From time to time, we have to fix phones for people. Today, an elderly woman is asking me to look at her phone.)

Customer: “There is something wrong with my phone. Could you fix it for me?”

Me: “Sure, what’s it doing?”

Customer: “Well, it won’t make any phone calls.”

Me: “No problem. Can I see your phone for a moment?”

(The customer digs through her purse, pulls out a calculator, and hands it to me.)

Customer: “See, I punch in a phone number and nothing happens.”

Me: “Erm, did you grab this by mistake? This is a calculator, not a cell phone.” *hands back the calculator*

(The customer takes the calculator back, looks at it, then looks at me blankly before walking away.)