You’re Just Compounding The Issue

(A customer has purchased a few items and is double-checking her receipt after the transaction went through. She has a membership card at the store, so she got a 10% discount.)

Customer: “So I got my discount on this?”

Me: “Yep. See there on each item, it says ‘Member 10%,’ and it shows what you saved.”

Customer: “Wait… is it 10% off each item, or 10% off the total?”

Me: “10% off the total. Well, it works out the same either way.”

Customer: “I thought it was supposed to be 10% off each item. I should be getting a bigger discount on the total.”

Me: “No, you got your discount! 10% off each item adds up to the same amount as 10% off the total.”

Customer: “No, I got 10% off the first item. Then 10% off the second item, so that’s 20%. And 10% off the third item; that’s 30%!”

Me: *pause* “No, that’s… that’s not how percentages work… I can show you on a calculator; it works out the same. You are getting the right discount.”

Customer: “No, it’s all right. But I know I won’t be getting this card again. I was told I was going to be getting a 10% discount on each item, and this really isn’t fair.”

(Maybe I should have mentioned to her that I’m a math major…)