Simply put, banks buy at low prices and sell at high prices. Such as: GBP/USD, the highest price1.6305; Lowest price1.6233; That is, you can use 1 to get 1.6233 dollars from the bank, and you must use 1 to get/kloc-0 dollars from the bank.

1. Bank of China buys US dollars from you at the highest price (selling price) of 1.6305.

2. You bought the pound at the highest price (selling price) 1.6305 in the Bank of China.

3. If it is sold to the Bank of China in pounds, the exchange rate is calculated at the lowest price (buying price) 1.6233.