A friend forwarded me an email for an online holiday sale:
We’ll be offering a coupon code for 10% off which will be in addition to the up to 20% you can take off your products. That’ll mean up to 28% off 1000s of products. Our promo code will be CMT12.
The reason it is up to 28% off and not 30% is because our 10% comes off your already discounted prices.
I appreciate them walking everyone through the math. Lots of neat student questions here:
- Is the email correct? Show it mathematically.
- What are two coupons I could combine to get 30% off?
- What other math do people often mess up? Write an email explaining their common mistake.