打折就是在原来售价的基础上降价销售，几折则表示实际售价占原来售价的成数。注意：10%就是一成，也就是一折，所以八折，就意味着实际售价是原来售价的80%。
A discount is a sale at a reduced price based on the original selling price. The discount indicates the percentage of the actual selling price to the original selling price. Note: 10% of the original selling price, which is 90% off; so 20% off means that the actual selling price is 80% of the original selling price.
打折 (dǎ zhé) 或者折扣 (zhé kòu)，是商品买卖中的让利、减价，是卖方给买方的价格优惠，但买卖双方给予或者接受折扣都要明示并如实入账。法律上对折扣的概念作了如下界定：本规定所称折扣，即商品购销中的让利，是指经营者在销售商品时，以明示并如实入账的方式给予对方的价格优惠，包括支付价款时对价款总额按一定比例即时予以扣除和支付价款总额后再按一定比例予以退还两种形式。折扣店是指以销售自有品牌和周转快的商品为主，限定销售品种，并以有限的经营面积、店铺装修简单、有限的服务和低廉的经营成本，向消费者提供“物有所值”的商品为主要目的的零售业态。
计算方法
1.原价×（折扣÷10）
例如：原价是70元，打三折，就是：70×（3÷10）=21。
例如：打八折，就是：原价×80%。
2.原价×折扣/10
例如：原价是40元，打五折，就是：40×5/10 =20。
3.原价×0.1折扣
列如：原价是100元，打一折，就是：100×0.1=10。
A discount (dǎ zhé) or discount (zhé kòu) is a profit-making or price reduction in the sale of goods. It is a price concession given by the seller to the buyer. However, both the buyer and the seller must clearly indicate and truthfully record the discount. The legal definition of discount is as follows: The discount referred to in these regulations, that is, the profit-making in the purchase and sale of goods, refers to the price concession given to the other party by the operator in the form of explicit indication and truthful accounting when selling goods, including immediate deduction of a certain proportion of the total price when paying the price and refunding a certain proportion after paying the total price. A discount store refers to a retail format that mainly sells its own brands and fast-turnover goods, limits the sales varieties, and provides consumers with “value for money” goods with limited business area, simple store decoration, limited services and low operating costs.
Calculation method
1. Original price × (discount ÷ 10)
For example: the original price is 70 yuan, 70% off, then the selling price after discount is: 70 × (3 ÷ 10) = 21.
For example: 20% off, then the selling price after discount is: original price × 80%.
2. Original price × discount / 10
For example: the original price is 40 yuan, 50% off, then the selling price after discount is: 40 × 5/10 = 20.
3. Original price × 0.1 discount
For example: the original price is 100 yuan, 90% off, then the selling price after discount is: 100 × 0.1 = 10.