In China, price reductions are shown in a different way from the rest of the world. In Europe and most other places, the saved amount is shown as a percentage, i.e. 20% off means that you buy the goods at 80% of the original price.
The Chinese system focuses on the price that you will have to pay rather than on the percentage you have saved. A saving of 80% will hence be written as 2折, meaning 2/10 of the original price. 15% is written 8.5折 and so forth.
Most travelers will be able to decode our pricing system, and international brands in China have begun to use the percentage system when marking discounted goods. However, doing something special for the Chinese will not go unnoticed and will make them feel welcome.