When a supermarket or clothing store says "30% off," it can be confusing to work out what you actually pay. Change the original price and discount rate with the sliders and see how the discount and final price are calculated.
How to calculate: Discount amount = original price × (discount rate ÷ 100). For example, with an original price of 10,000 won and a 30% discount, the discount is 10,000 × 0.3 = 3,000 won, and the price you pay is 10,000 − 3,000 = 7,000 won.
There is a faster way: a 30% discount means you pay only 70% of the original price, so you can calculate 10,000 × 0.7 = 7,000 won in one step. Multiply the original price by (100% − discount rate) to get the sale price directly.