Combined calculation of foreign exchange purchase and settlement amount. If you change $30,000 into RMB and then use RMB to buy $20,000, your amount will be used up in the bank's foreign exchange settlement system. When you need to handle the US dollar settlement business this year, you need to go to the bank to submit a certificate to go through the relevant procedures, but it is 50,000 US dollars per person per year, which is a convenient amount. In other words, each person only needs to provide his/her ID card for settlement of foreign exchange within 50,000 yuan (the sum of all banks) and purchase of foreign exchange within 50,000 yuan per year, but he/she needs to bring relevant supporting materials to the counter for more than 50,000 yuan. For example, it is also allowed to charge more than $60,000 for summer camps abroad. 50,000 yuan, that is, the convenient amount of materials is not needed, and mobile banking can also be operated. The surplus can only be found at the counter, and there are relevant supporting materials.